If x = (4t^2)/(5t^2+6) x=4t25t2+6, and y = t^3 y=t3 then find dy/dxdydx?

1 Answer
Feb 9, 2018

dy/dx = (t(5t^2+6)^2) / (16) dydx=t(5t2+6)216

Explanation:

We have:

x = (4t^2)/(5t^2+6) x=4t25t2+6, and y = t^3 y=t3

Differentiating wrt tt we have (using the quotient rule):

dx/dt = ( (5t^2+6)(8t) - (10t)(4t^2) ) / (5t^2+6)^2 dxdt=(5t2+6)(8t)(10t)(4t2)(5t2+6)2

\ \ \ \ \ \ = ( 40t^3+48t - 40t^3) / (5t^2+6)^2

\ \ \ \ \ \ = ( 48t) / (5t^2+6)^2

dy/dt = 3t^2

Then, By the chain rule, we have:

dy/dx = (dy//dt)/(dx//dt)

\ \ \ \ \ \ = (3t^2) / (( 48t) / (5t^2+6)^2)

\ \ \ \ \ \ = ((3t^2)(5t^2+6)^2) / (48t)

\ \ \ \ \ \ = (t(5t^2+6)^2) / (16)