The abscissa (x-coordinate) and ordinate (y-coordinate) change at the same rate means:
dtdx=dtdy
where t represents time.
Given the curve y2=8x, differentiate both sides with respect to time t:
2y⋅dtdy=8⋅dtdx
Since dtdx=dtdy, substitute:
2y⋅dtdx=8⋅dtdx
Dividing both sides by dtdx:
2y=8
y=4
Substitute y=4 into the curve equation y2=8x:
(4)2=8x
16=8x
x=2
Therefore, the point is (2,4).