# Homework Help: Derivative school work help

1. Jul 22, 2010

### annoymage

1. The problem statement, all variables and given/known data

let x=et and define y(x(t))=Y(t)

Show that x(d/dx)y=(d/dt)Y

2. Relevant equations

n/a

3. The attempt at a solution

i try using chain rule but

x(dy/dt)(dt/dx) and i dont know how to make it to be dY/dt, and i don't have clue what is the point of x=et.. help T_T

2. Jul 22, 2010

### HallsofIvy

Re: derivative

Look at it the other way around. If $x= e^t$ then $dy/dt= (dy/dx)(dx/dt)= e^t(dy/dx)= x(dy/dx)$. The point of "$x= e^t$ is that the derivative of $x= e^t$ is $x= e^t$.

3. Jul 22, 2010

### annoymage

Re: derivative

my goodness, thank you very very very much