Hello!

I have this function $\displaystyle f(x)=1,2x^5-4x^3$ and I need to give the intervals where the function's graph is concave and convex.

I know $\displaystyle f'(x)=0$ when $\displaystyle x=\sqrt{2}$, $\displaystyle x=-\sqrt{2}$ and $\displaystyle x=0$

Thanks in advance!