# Finding the turning point

• Dec 2nd 2009, 02:05 PM
Paymemoney
Finding the turning point
Hi
I'm having trouble finding the turning point(max & min) of this equation and also the stationary points and x-intercepts.

$y=9(x-1)^2-(x-1)^4$

P.S
• Dec 2nd 2009, 02:24 PM
Bacterius
The x-intercepts are the points where the curve hits the x-axis. Do you mean you have trouble solving $f(x) = 0$ for $x$ ?

Think about using the derivative. When the derivative is $0$ in a point, the function is very likely to turn round at this point (although sometimes it doesn't).
Steps :
- get the derivative $f'(x)$ of your function $f(x)$
- solve for $x$ with $f'(x) = 0$
- ensure each point found is indeed a turning point (you should know how to do this last step)

Does it make sense ?
• Dec 2nd 2009, 05:29 PM
Paymemoney
yeh it makes sense, thanks for the help