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question:In the xy-plane, what is the length of the shortest path from (0,0) to (15,20) that does not go inside the circles (x-7.5)^{2}+(y-10)^{2}= 36 and (x-15)^{2}+(y-5)^2 = 16?A) 31 + frac{5pi}{3}B) 30 + 5piC) 20 + 4piD) 30.6 + frac{5pi}{3}

answer:Okay, so I have this problem where I need to find the shortest path from the point (0,0) to (15,20) in the xy-plane. But there's a catch: I can't go inside two specific circles. The circles are given by the equations ((x - 7.5)^2 + (y - 10)^2 = 36) and ((x - 15)^2 + (y - 5)^2 = 16). First, I should probably visualize this. The first circle is centered at (7.5, 10) with a radius of 6 because 36 is 6 squared. The second circle is centered at (15, 5) with a radius of 4 because 16 is 4 squared. So, I need to go from (0,0) to (15,20) without entering either of these circles.I remember that the shortest path avoiding obstacles often involves tangents to the obstacles. So, maybe I can find a path that just touches these circles without going inside them. That way, the path would be as short as possible.Let me think about how to approach this. I think I need to find tangent lines from (0,0) to the first circle and from (15,20) to the second circle. Then, connect these tangents with an arc around each circle. But I'm not entirely sure how to calculate the exact points where the tangents touch the circles.Maybe I should start by calculating the distance from (0,0) to the center of the first circle, which is (7.5, 10). Using the distance formula, that would be sqrt[(7.5 - 0)^2 + (10 - 0)^2] = sqrt[56.25 + 100] = sqrt[156.25] = 12.5. Since the radius of the first circle is 6, the length of the tangent from (0,0) to the circle would be sqrt[12.5^2 - 6^2] = sqrt[156.25 - 36] = sqrt[120.25] = 11. So, the tangent from (0,0) to the first circle is 11 units long.Similarly, I should calculate the distance from (15,20) to the center of the second circle, which is (15,5). Using the distance formula again, that's sqrt[(15 - 15)^2 + (20 - 5)^2] = sqrt[0 + 225] = 15. The radius of the second circle is 4, so the length of the tangent from (15,20) to the second circle would be sqrt[15^2 - 4^2] = sqrt[225 - 16] = sqrt[209] ≈ 14.456. Hmm, so the tangent from (15,20) to the second circle is approximately 14.456 units long.Now, I need to figure out the angle between these tangents and how much of the circles' circumferences I need to include in the path. Maybe I can find the angle between the line connecting the centers of the circles and the tangent points.The distance between the centers of the two circles is sqrt[(15 - 7.5)^2 + (5 - 10)^2] = sqrt[56.25 + 25] = sqrt[81.25] ≈ 9.0139. I think I can use the law of cosines to find the angle at the center of the first circle. The sides of the triangle would be the distance from (0,0) to the center of the first circle (12.5), the radius of the first circle (6), and the distance between the centers (≈9.0139). Wait, maybe it's better to consider the triangle formed by the centers of the circles and the tangent points. The angle at the center of the first circle can be found using the cosine law: cos(theta) = (6^2 + 9.0139^2 - 12.5^2)/(2*6*9.0139). Let me compute that.First, compute 6^2 = 36, 9.0139^2 ≈ 81.25, and 12.5^2 = 156.25. So, cos(theta) = (36 + 81.25 - 156.25)/(2*6*9.0139) = (-39)/(108.1668) ≈ -0.3607. So, theta ≈ arccos(-0.3607) ≈ 111 degrees. Hmm, that seems a bit large. Maybe I made a mistake in the calculation. Let me double-check.Wait, actually, the triangle I should be considering is the one formed by the centers of the circles and the tangent points. The sides would be the radii and the distance between the centers. So, maybe I should use the angle between the line connecting the centers and the tangent line.Alternatively, I remember that the angle between the tangent and the line connecting the center to the external point can be found using sin(theta) = radius / distance from external point to center. So, for the first circle, sin(theta1) = 6 / 12.5 = 0.48, so theta1 ≈ arcsin(0.48) ≈ 28.68 degrees. Similarly, for the second circle, sin(theta2) = 4 / 15 ≈ 0.2667, so theta2 ≈ arcsin(0.2667) ≈ 15.47 degrees.Now, the total angle around the first circle that the path would take is 180 - 2*theta1 ≈ 180 - 57.36 ≈ 122.64 degrees. Similarly, around the second circle, it's 180 - 2*theta2 ≈ 180 - 30.94 ≈ 149.06 degrees.Wait, but I think I might be overcomplicating this. Maybe I should just calculate the arc lengths based on the angles I found earlier.For the first circle, the angle was approximately 111 degrees, which is roughly 1.936 radians. The arc length would be radius * angle = 6 * 1.936 ≈ 11.616. For the second circle, the angle was approximately 149.06 degrees, which is roughly 2.6 radians. The arc length would be 4 * 2.6 ≈ 10.4.But I'm not sure if these angles are correct. Maybe I should use the angle between the two tangent lines from the external points.Alternatively, perhaps I should consider the angle between the two tangent points on each circle. Since the path goes from (0,0) to the first circle, follows an arc, then goes to the second circle, follows another arc, and finally to (15,20). I think the key is to find the angles at the centers of the circles that correspond to the points where the tangents touch. Then, the arc lengths can be calculated as a fraction of the circumference based on those angles.Let me try to calculate the angle at the center of the first circle. The distance from (0,0) to the center is 12.5, and the radius is 6. So, the angle can be found using the cosine law in the triangle formed by (0,0), the center, and the tangent point.Wait, actually, in the triangle formed by (0,0), the center of the first circle, and the tangent point, we have two sides: 12.5 (from (0,0) to center) and 6 (radius). The angle at the center is opposite the tangent line, which we found earlier to be approximately 111 degrees.So, the arc length on the first circle would be (111/360) * 2π*6 ≈ (0.3083) * 12π ≈ 3.7π ≈ 11.616.Similarly, for the second circle, the angle at the center is approximately 149.06 degrees, so the arc length would be (149.06/360) * 2π*4 ≈ (0.414) * 8π ≈ 3.312π ≈ 10.4.But I'm not sure if these angles are accurate. Maybe I should use the angle between the two tangent lines from the external points.Alternatively, perhaps I should use the angle between the line connecting the centers and the tangent points. Wait, I think I need to find the angle between the line connecting the centers and the tangent line. For the first circle, the angle theta1 is arcsin(6/12.5) ≈ 28.68 degrees. Similarly, for the second circle, theta2 ≈ arcsin(4/15) ≈ 15.47 degrees.So, the angle between the two tangent points on the first circle would be 180 - 2*theta1 ≈ 180 - 57.36 ≈ 122.64 degrees. Similarly, on the second circle, it's 180 - 2*theta2 ≈ 149.06 degrees.Therefore, the arc lengths would be (122.64/360)*2π*6 ≈ (0.3407)*12π ≈ 4.088π ≈ 12.84, and for the second circle, (149.06/360)*2π*4 ≈ (0.414)*8π ≈ 3.312π ≈ 10.4.Wait, but I'm getting different arc lengths depending on the method. I think I need to clarify which angle corresponds to the arc that the path takes around each circle.Maybe the correct approach is to find the angle between the two tangent points on each circle as seen from the center. For the first circle, the angle would be the angle between the two tangent lines from (0,0). Similarly, for the second circle, the angle between the two tangent lines from (15,20).But I'm not sure how to calculate that angle. Maybe I can use the distance between the centers and the radii to find the angle.Alternatively, perhaps I can use the fact that the path from (0,0) to (15,20) without entering the circles will consist of two tangent lines and two arcs. The total path length would be the sum of the lengths of the two tangents and the two arcs.Wait, but in the answer choices, I see options with pi terms, which suggests that the arcs are significant. So, maybe the path goes around each circle by a certain angle, and the total path is the sum of the straight tangents and the arcs.Let me try to calculate the angles again. For the first circle, the angle at the center is 2*arcsin(6/12.5) ≈ 2*28.68 ≈ 57.36 degrees. Similarly, for the second circle, it's 2*arcsin(4/15) ≈ 2*15.47 ≈ 30.94 degrees.Wait, no, that's the angle between the two tangent lines from the external point. So, the arc that the path takes around the first circle would be 360 - 57.36 ≈ 302.64 degrees, which seems too large. That can't be right because the path shouldn't go all the way around the circle.I think I'm confusing the angle between the tangents with the angle of the arc that the path takes. Maybe the arc is actually the angle that the path turns around the circle, which would be supplementary to the angle between the tangents.Wait, perhaps the arc is the angle that the path turns around the circle, which would be 180 - theta, where theta is the angle between the tangent and the line connecting the external point to the center.So, for the first circle, theta1 ≈ 28.68 degrees, so the arc angle would be 180 - 28.68 ≈ 151.32 degrees. Similarly, for the second circle, theta2 ≈ 15.47 degrees, so the arc angle would be 180 - 15.47 ≈ 164.53 degrees.But that still seems too large. Maybe I need to think differently.Alternatively, perhaps the path goes from (0,0) to a tangent point on the first circle, follows an arc around the first circle to another tangent point, then goes to a tangent point on the second circle, follows an arc around the second circle, and finally to (15,20). But that seems complicated.Wait, maybe the path only touches each circle once, so it's just one tangent from (0,0) to the first circle, then an arc around the first circle to a point where another tangent can be drawn to the second circle, then another arc around the second circle, and finally a tangent to (15,20). But I'm not sure.Alternatively, perhaps the path goes from (0,0) to a tangent point on the first circle, then follows an arc around the first circle to a point where it can go to a tangent point on the second circle, then follows an arc around the second circle to (15,20). But this might involve multiple arcs.Wait, maybe it's simpler. The shortest path would consist of two straight tangents and two arcs. The total length would be the sum of the lengths of the two tangents and the two arcs.So, the total length would be:Length = tangent1 + arc1 + tangent2 + arc2But I need to find the lengths of tangent1, tangent2, arc1, and arc2.I already calculated tangent1 ≈ 11 and tangent2 ≈ 14.456.Now, for arc1, I need to find the angle that the path turns around the first circle. Similarly, for arc2, the angle around the second circle.Wait, perhaps the angle around each circle is determined by the angle between the two tangent points as seen from the center of the circle.For the first circle, the angle between the two tangent points (from (0,0) and to the second circle) can be found using the cosine law in the triangle formed by the centers and the tangent points.Wait, maybe I can calculate the angle between the two tangent points on the first circle by considering the triangle formed by the centers of the circles and the tangent points.The distance between the centers is ≈9.0139, the radius of the first circle is 6, and the radius of the second circle is 4.Wait, actually, the angle at the center of the first circle can be found using the cosine law:cos(theta) = (6^2 + 9.0139^2 - (distance between tangent points)^2)/(2*6*9.0139)But I don't know the distance between the tangent points. Hmm, maybe this approach isn't working.Alternatively, perhaps I can use the fact that the two tangent lines from (0,0) and (15,20) to the circles form similar triangles.Wait, maybe I should consider the external homothety center of the two circles. The homothety center would be the point where the external tangents intersect. But I'm not sure if that's necessary here.Alternatively, perhaps I can parameterize the path and minimize the total length, but that seems too complex.Wait, maybe I can use the fact that the shortest path will touch each circle exactly once, so it will have two tangent segments and two arcs.But I'm not sure how to calculate the exact angles for the arcs.Wait, looking at the answer choices, I see that option D is 30.6 + (5π)/3. The other options have different combinations. So, maybe the total path is approximately 30.6 plus a certain arc length.Given that, perhaps the total straight segments are approximately 30.6, and the arcs add up to (5π)/3.Wait, let me think. The straight segments from (0,0) to the first circle is 11, from the second circle to (15,20) is approximately 14.456, and the distance between the tangent points on the circles would be the straight line between them, which is the distance between the centers minus the radii? Wait, no, that's not correct.Wait, the distance between the tangent points on the two circles would be the distance between the centers minus the sum of the radii? No, that's for internal tangents. For external tangents, it's the distance between centers minus the difference of the radii? Hmm, I'm getting confused.Wait, perhaps the distance between the tangent points is the same as the length of the external tangent between the two circles. The length of the external tangent between two circles with radii r1 and r2 and centers separated by distance d is sqrt[d^2 - (r1 + r2)^2]. Wait, no, that's for internal tangents. For external tangents, it's sqrt[d^2 - (r1 - r2)^2].So, in this case, d ≈9.0139, r1=6, r2=4. So, the length of the external tangent is sqrt[9.0139^2 - (6 - 4)^2] = sqrt[81.25 - 4] = sqrt[77.25] ≈8.79.So, the distance between the tangent points on the two circles is approximately8.79.But wait, if the path goes from (0,0) to the first circle, then along an arc to the external tangent point, then along the external tangent to the second circle, then along an arc to (15,20), the total length would be:tangent1 + arc1 + external tangent + arc2 + tangent2.But I'm not sure if that's the case.Alternatively, maybe the path goes from (0,0) to the first circle, follows an arc around the first circle to a point where it can go directly to the second circle, then follows an arc around the second circle to (15,20). But that might involve more complex calculations.Wait, perhaps the shortest path is composed of two straight tangents and two arcs, where the arcs are the parts of the circles that the path follows to avoid going inside.Given that, the total length would be:Length = tangent1 + arc1 + tangent2 + arc2But I need to find the lengths of tangent1, tangent2, arc1, and arc2.I already have tangent1 ≈11 and tangent2≈14.456.Now, for arc1 and arc2, I need to find the angle that the path turns around each circle.Wait, perhaps the angle around each circle is determined by the angle between the tangent and the line connecting the center to the external point.For the first circle, the angle theta1 ≈28.68 degrees, so the arc would be 180 - 2*theta1 ≈122.64 degrees.Similarly, for the second circle, theta2≈15.47 degrees, so the arc would be 180 - 2*theta2≈149.06 degrees.But wait, that would mean the path turns around each circle by those angles, which seems too much.Alternatively, perhaps the arc is just the angle between the two tangent points as seen from the center of the circle.Wait, for the first circle, the angle between the two tangent points (from (0,0) and to the external tangent) can be found using the cosine law.The sides of the triangle would be the distance from (0,0) to the center (12.5), the radius (6), and the distance between the centers (≈9.0139).Wait, no, that's not the triangle. The triangle should be formed by the center of the first circle, the tangent point on the first circle, and the tangent point on the second circle.But I don't know the distance between the tangent points.Alternatively, perhaps I can use the angle between the two tangent lines from (0,0) to the first circle. That angle is 2*theta1≈57.36 degrees.Similarly, for the second circle, it's 2*theta2≈30.94 degrees.But I'm not sure how that helps with the arc length.Wait, maybe the arc length is the angle between the two tangent points as seen from the center, which would be 180 - 2*theta1 for the first circle and 180 - 2*theta2 for the second circle.So, for the first circle, arc1≈122.64 degrees, which is≈2.14 radians. Arc length=6*2.14≈12.84.For the second circle, arc2≈149.06 degrees, which is≈2.6 radians. Arc length=4*2.6≈10.4.But then the total length would be≈11 +12.84 +14.456 +10.4≈48.696, which is way too long compared to the answer choices.Wait, the answer choices are around 30-31 plus some pi terms. So, maybe my approach is wrong.Perhaps the path doesn't go around both circles but only one. Wait, but there are two circles to avoid. So, the path must go around both.Wait, maybe the path goes from (0,0) to a tangent point on the first circle, follows an arc around the first circle to a point where it can go directly to (15,20) without entering the second circle. But that might not work because the second circle is in the way.Alternatively, maybe the path goes from (0,0) to a tangent point on the first circle, then to a tangent point on the second circle, and then to (15,20). But that would involve two straight tangents and no arcs, which might not be the shortest path.Wait, but the answer choices have pi terms, which suggests that the path includes arcs. So, maybe the path goes around each circle by a certain angle, adding to the total length.Wait, perhaps the path goes from (0,0) to a tangent point on the first circle, follows an arc around the first circle to a point where it can go directly to (15,20) without entering the second circle. But I'm not sure.Alternatively, maybe the path goes from (0,0) to a tangent point on the first circle, then follows an arc around the first circle to a point where it can go to a tangent point on the second circle, then follows an arc around the second circle to (15,20). But that would involve two arcs.Wait, maybe I should consider the angles at which the path approaches and leaves each circle. For the first circle, the angle is theta1≈28.68 degrees, and for the second circle, theta2≈15.47 degrees.So, the total angle turned around the first circle would be 180 - 2*theta1≈122.64 degrees, and around the second circle≈149.06 degrees.But converting these to radians, 122.64 degrees≈2.14 radians, and 149.06≈2.6 radians.So, arc1=6*2.14≈12.84, arc2=4*2.6≈10.4.But then the total length would be≈11 +12.84 +14.456 +10.4≈48.696, which is too long.Wait, maybe I'm overcomplicating it. Perhaps the path only goes around one circle and not the other. But there are two circles to avoid, so that might not be possible.Wait, looking at the answer choices, option D is 30.6 + (5π)/3≈30.6 +5.236≈35.836. That seems more reasonable.So, maybe the total straight segments are≈30.6, and the arcs add up to≈5.236.Wait, 5π/3≈5.236, which is the arc length. So, maybe the path goes from (0,0) to a tangent point on the first circle, follows an arc of 5π/3≈5.236, then goes straight to (15,20).But how does that avoid the second circle?Wait, maybe the path goes from (0,0) to a tangent point on the first circle, follows an arc around the first circle, then goes straight to (15,20), avoiding the second circle.But I'm not sure if that's possible because the second circle is at (15,5), which is close to (15,20). So, the straight path from the arc to (15,20) might pass near the second circle.Alternatively, maybe the path goes from (0,0) to a tangent point on the first circle, follows an arc around the first circle to a point where it can go directly to (15,20) without entering the second circle.But I need to make sure that the straight path from the arc to (15,20) doesn't enter the second circle.Alternatively, perhaps the path goes from (0,0) to a tangent point on the first circle, follows an arc around the first circle to a point where it can go to a tangent point on the second circle, then follows an arc around the second circle to (15,20).But that would involve two arcs, which might add up to more than 5π/3.Wait, maybe the total arc length is 5π/3, which is≈5.236. So, if the total arc length is 5π/3, then the straight segments would be≈30.6.So, total length≈30.6 +5.236≈35.836.But I'm not sure how to get the straight segments to be≈30.6.Wait, the straight line distance from (0,0) to (15,20) is sqrt(15^2 +20^2)=25. So, the path is longer than 25 because it has to go around the circles.But the answer choices are around 30-31 plus some pi terms, which suggests that the total path is≈30-31 plus≈5.236, totaling≈35-36.Wait, but the straight line distance is 25, so the path has to be longer than that. The answer choices are all above 30, which makes sense.Wait, maybe the total straight segments are≈30.6, and the arcs add≈5.236, making the total≈35.836.But I need to verify how to get the straight segments to be≈30.6.Wait, the straight segments are the tangents from (0,0) to the first circle and from the second circle to (15,20). I calculated those as≈11 and≈14.456, totaling≈25.456. But 25.456 is less than 30.6, so maybe I'm missing something.Wait, perhaps the path also includes the distance between the tangent points on the two circles, which I calculated earlier as≈8.79. So, total straight segments≈11 +8.79 +14.456≈34.246, which is close to 30.6 +5.236≈35.836.But 34.246 is less than 35.836, so maybe the arc length is≈1.59 added to the straight segments.Wait, I'm getting confused. Maybe I should look for a different approach.I remember that the shortest path avoiding two circles can be found by considering the external tangents and the arcs around each circle. The total path length would be the sum of the lengths of the two external tangents and the arcs around each circle.But I need to find the angles of the arcs.Wait, perhaps the angle around each circle is determined by the angle between the external tangent and the line connecting the center to the external point.For the first circle, the angle theta1≈28.68 degrees, so the arc would be 180 - 2*theta1≈122.64 degrees≈2.14 radians. Arc length=6*2.14≈12.84.For the second circle, theta2≈15.47 degrees, so the arc would be 180 - 2*theta2≈149.06 degrees≈2.6 radians. Arc length=4*2.6≈10.4.But then the total arc length≈12.84 +10.4≈23.24, which is too much.Wait, but the answer choices have only one pi term, so maybe the total arc length is just one arc, not two.Wait, maybe the path goes around one circle and not the other. But there are two circles to avoid, so that might not be possible.Alternatively, maybe the path goes around the first circle by an angle of 5π/3≈5.236, which is≈300 degrees, which seems too much.Wait, 5π/3 is≈5.236 radians≈300 degrees. That would mean the path goes around the first circle by 300 degrees, which is most of the circle, which seems inefficient.Alternatively, maybe the path goes around the first circle by 60 degrees, which is π/3≈1.047 radians, and the second circle by 120 degrees, which is 2π/3≈2.094 radians. Then, total arc length≈6*(π/3) +4*(2π/3)=2π +8π/3≈10π/3≈10.472.But that's still more than the answer choices.Wait, maybe the path only goes around one circle by 5π/3≈5.236, which is≈300 degrees, and doesn't go around the other circle. But that seems unlikely because the second circle is also in the way.Wait, perhaps the path goes from (0,0) to a tangent point on the first circle, follows an arc of 5π/3 around the first circle, then goes straight to (15,20). But I need to check if that straight path avoids the second circle.Alternatively, maybe the path goes from (0,0) to a tangent point on the first circle, follows an arc of 5π/3 around the first circle, then goes to a tangent point on the second circle, and then to (15,20). But that would involve two arcs.Wait, I'm getting stuck. Maybe I should look for a different method.I remember that the shortest path avoiding two circles can be found by considering the Minkowski sum or using some geometric transformations, but that might be too advanced.Alternatively, maybe I can use the fact that the shortest path will touch each circle exactly once, so it will have two tangent segments and two arcs. The total length would be the sum of the lengths of the two tangents and the two arcs.Given that, and knowing that the answer choices have a pi term, I think the total arc length is 5π/3≈5.236.So, if the total arc length is 5π/3, then the straight segments must be≈30.6.So, total length≈30.6 +5.236≈35.836.But how do I get the straight segments to be≈30.6?Wait, the straight segments are the tangents from (0,0) to the first circle and from the second circle to (15,20). I calculated those as≈11 and≈14.456, totaling≈25.456. So, the remaining distance must be the distance between the tangent points on the two circles, which I calculated earlier as≈8.79.So, total straight segments≈11 +8.79 +14.456≈34.246, which is close to 30.6 +5.236≈35.836.But 34.246 is less than 35.836, so maybe the arc length is≈1.59 added to the straight segments.Wait, I'm not sure. Maybe I should accept that the total arc length is 5π/3 and the straight segments are≈30.6, making the total≈35.836, which matches option D.So, I think the answer is D) 30.6 + (5π)/3.

question:Determine the area of the shaded region if the radius of the larger circle is five times that of the smaller circle and the diameter of the smaller circle is 6 units. The shaded region is the area between the two circles.

answer:First, determine the radius of the smaller circle by dividing its diameter by 2. Given that the diameter is 6 units, the radius is 3 units.Next, calculate the radius of the larger circle, which is five times the radius of the smaller circle. This gives a radius of 15 units for the larger circle.Then, find the area of the larger circle using the formula ( pi R^2 ), resulting in ( 225pi ) square units.Similarly, calculate the area of the smaller circle using the formula ( pi r^2 ), which equals ( 9pi ) square units.Finally, subtract the area of the smaller circle from the area of the larger circle to find the area of the shaded region: ( 225pi - 9pi = 216pi ) square units.

question:Among the following shapes, the one that is both axially symmetric and centrally symmetric is ( ):A: ParallelogramB: CircleC: Equilateral triangleD: Regular pentagon

answer:To determine which shape is both axially symmetric and centrally symmetric, let's analyze each option:1. **Parallelogram (A):** A parallelogram is centrally symmetric because it has a center of symmetry. However, it is not axially symmetric because it does not have a line of symmetry.2. **Circle (B):** A circle is both axially symmetric and centrally symmetric. It has infinite lines of symmetry and a single center of symmetry.3. **Equilateral Triangle (C):** An equilateral triangle is axially symmetric because it has three lines of symmetry. However, it is not centrally symmetric.4. **Regular Pentagon (D):** A regular pentagon is axially symmetric because it has five lines of symmetry. However, it is not centrally symmetric.Based on this analysis, the circle is the only shape that is both axially symmetric and centrally symmetric.

question:If the function f(x) is an odd function, and when x geq 0, f(x) = x^2 + x, then the value of f(-3) is.

answer:First, I recognize that the function ( f(x) ) is an odd function, which means that ( f(-x) = -f(x) ) for all ( x ).Given that ( f(x) = x^2 + x ) when ( x geq 0 ), I can find ( f(3) ) by substituting ( x = 3 ) into the equation:[f(3) = 3^2 + 3 = 9 + 3 = 12]Since ( f(x) ) is an odd function, ( f(-3) = -f(3) ). Therefore:[f(-3) = -12]

question:Given vectors overrightarrow{a} = (1, 2) and overrightarrow{b} = (x, -2), and overrightarrow{a} perp overrightarrow{b}, then |overrightarrow{a} + overrightarrow{b}| = (  )A: 5B: sqrt{5}C: 4sqrt{2}D: sqrt{31}

answer:First, I recognize that vectors (overrightarrow{a}) and (overrightarrow{b}) are perpendicular, which means their dot product is zero.Given (overrightarrow{a} = (1, 2)) and (overrightarrow{b} = (x, -2)), I set up the equation for the dot product:[1 times x + 2 times (-2) = 0]Solving for (x), I find:[x - 4 = 0 quad Rightarrow quad x = 4]Now, I can determine the vector (overrightarrow{a} + overrightarrow{b}):[overrightarrow{a} + overrightarrow{b} = (1 + 4, 2 + (-2)) = (5, 0)]Finally, I calculate the magnitude of (overrightarrow{a} + overrightarrow{b}):[|overrightarrow{a} + overrightarrow{b}| = sqrt{5^2 + 0^2} = sqrt{25} = 5]

question:The parabola with equation y=ax^2+bx+c is graphed below:[asy]xaxis(-3,7);yaxis(-5,32);real g(real x){return 4(x-2)^2-4;}draw(graph(g,-1,5));dot((2,-4));label("Vertex: (2,-4)", (2,-4), SE);dot((4,12));label("(4,12)", (4,12), E);[/asy]The zeros of the quadratic ax^2 + bx + c are at x=m and x=n, where m>n. What is m-n?

answer:Okay, so I have this problem about a parabola with the equation y = ax² + bx + c. The graph is provided, and I can see that it has a vertex at (2, -4) and another point at (4, 12). The question is asking for the difference between the zeros of the quadratic, which are at x = m and x = n, with m being greater than n. So, I need to find m - n.First, I remember that the vertex form of a parabola is y = a(x - h)² + k, where (h, k) is the vertex. Given that the vertex is (2, -4), I can write the equation as y = a(x - 2)² - 4. Now, I need to find the value of 'a'. To do that, I can use the other point given, which is (4, 12). So, substituting x = 4 and y = 12 into the equation:12 = a(4 - 2)² - 4Simplifying that:12 = a(2)² - 412 = 4a - 4Adding 4 to both sides:16 = 4aDividing both sides by 4:a = 4Okay, so now I know that a = 4. So the equation of the parabola is y = 4(x - 2)² - 4. Next, I need to find the zeros of this quadratic, which are the x-values where y = 0. So, I set y to 0 and solve for x:0 = 4(x - 2)² - 4Let me solve this step by step. First, add 4 to both sides:4 = 4(x - 2)²Then, divide both sides by 4:1 = (x - 2)²Now, take the square root of both sides:√1 = |x - 2|Which means:x - 2 = ±1So, solving for x:x = 2 + 1 = 3orx = 2 - 1 = 1Therefore, the zeros are at x = 3 and x = 1. Since m > n, m is 3 and n is 1. So, m - n = 3 - 1 = 2.Wait, let me double-check my steps to make sure I didn't make a mistake. I started with the vertex form, substituted the point (4,12) to find 'a', which gave me a = 4. Then, I set y = 0 and solved the equation, which led me to x = 3 and x = 1. The difference between these zeros is indeed 2. I think that's correct. The difference between the zeros is 2.

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