Critical point of $f(x)=(x^2-1)^2(x-3)^2$ Determine the critical point of $$f(x)=(x^2-1)^2(x-3)^2$$


Firstly, I get the derivative of $f(x)$. I got $=4x(x^2-1)(x-3)^2+2(x-3)(x^2-1)^2$. Any help will be appreciated.
Now, note that\begin{align}4x(x^2-1)(x-3)^2+2(x-3)(x^2-1)^2&amp;=2(x^2-1)(x-3)\bigl(2x(x-3)+x^2-1\bigr)\\&amp;=2(x^2-1)(x-3)(3x^2-6x-1).\end{align}Can you take it from here?
If you are allowed to use critical points calculator, here is solution at
Wolfram|Alpha service.