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The point on the curve y2=8xy^2 = 8x for which the abscissa and ordinate change at the same rate, is

Solution

✅ Correct Option: 2

The abscissa (x-coordinate) and ordinate (y-coordinate) change at the same rate means:

dxdt=dydt\frac{dx}{dt} = \frac{dy}{dt}

where tt represents time.


Given the curve y2=8xy^2 = 8x, differentiate both sides with respect to time tt:

2y⋅dydt=8⋅dxdt2y \cdot \frac{dy}{dt} = 8 \cdot \frac{dx}{dt}


Since dxdt=dydt\frac{dx}{dt} = \frac{dy}{dt}, substitute:

2y⋅dxdt=8⋅dxdt2y \cdot \frac{dx}{dt} = 8 \cdot \frac{dx}{dt}

Dividing both sides by dxdt\frac{dx}{dt}:

2y=82y = 8

y=4y = 4


Substitute y=4y = 4 into the curve equation y2=8xy^2 = 8x:

(4)2=8x(4)^2 = 8x

16=8x16 = 8x

x=2x = 2


Therefore, the point is (2,4)(2, 4).

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