A particle moves along the curve y = x3. Find the points on the curve at which the y - coordinate changes three times more rapidly than the x - coordinate.
Given: a particle moves along the curve y = x3.
To find the points on the curve at which the y - coordinate changes three times more rapidly than the x - coordinate
Equation of curve is y = x3
Differentiating the above equation with respect to t, we get
When y - coordinate changes three times more rapidly than the x - coordinate, i.e.,
Equating equation (i) and equation (ii), we get
⇒ x2 = 1 ⇒ x = ±1
When x = 1, y = x3 = (1)3⇒ y = 1
When x = - 1, y = x3 = ( - 1)3⇒ y = - 1
Hence the points on the curve at which the y - coordinate changes three times more rapidly than the x - coordinate are (1, 1) and ( - 1, - 1).