# Thread: Differentiating y(x)

1. ## Differentiating y(x)

hi guys can you help me this please:

Suppose y=f(x) is a curve that always lies above the x-axis and never has a horizontal tangent, where f is differentiable everywhere. For what value of y is the rate of change of y^5 with respect to x eighty times the rate of change of y with respect to x?

This question is under a chapter that deals with Chain Rule, if that helps.

I thought it might be something like this:
$\displaystyle 5y^4=80\frac{dy}{dx }$

2. Originally Posted by RezMan
hi guys can you help me this please:

Suppose y=f(x) is a curve that always lies above the x-axis and never has a horizontal tangent, where f is differentiable everywhere. For what value of y is the rate of change of y^5 with respect to x eighty times the rate of change of y with respect to x?

This question is under a chapter that deals with Chain Rule, if that helps.

I thought it might be something like this:
$\displaystyle 5y^4=80\frac{dy}{dx }$
it should be $\displaystyle 5y^4 \frac{dy}{dx}=80\frac{dy}{dx }$