# Homework Help: Inverse function

1. Nov 12, 2005

### Stun

how do I find the inverse function of y=xSqrt -2X

I have tried transposing it 6 times now but my results don't give the right answer for a 1:1 function for x<0

2. Nov 12, 2005

### HallsofIvy

I assume you mean to find the inverse function for $f(x)= x\sqrt{-2x}[/tex] for x< 0. Finding an inverse function is exactly the same a solving an equation. The point of "inverse" is that if [itex]y= f(x)= x\sqrt{-2x}$, then $x= y\sqrt{-2y}$. Solve that equation for y. (You will need to square both sides and eventually solve a cubic equation.)

3. Nov 12, 2005

### Stun

No that's not what I meant but not to worry i found the solution with touch more effort.