sketch f(x)=(x^{2}-1)^{3 }

Not sure where i am going wrong but when i look at the actual graph of this i cannot figure out the concavity. Could someone please help me out.

so far i have found f'(x)=6x^{5}-12x^{3}+6x and f''(x)=30x^{4}-36x^{2}+6

Thank you

Dylan Renke