<s>[INST] Simplify - Help I am supposed to simplify this:
$$(x^2-1)^2 (x^3+1) (3x^2) + (x^3+1)^2 (x^2-1) (2x)$$
The answer is supposed to be this, but I can not seem to get to it:
$$x(x^2-1)(x^3+1)(5x^3-3x+2)$$
Thanks
 [/INST] $$(x^2-1)^2 (x^3+1) (3x^2) + (x^3+1)^2 (x^2-1) (2x)\\=x(x^2-1)(x^3+1)\left[3x(x^2-1)+2(x^3+1)\right] \color{blue}{\text{(Factor out common factors)}}\\=x(x^2-1)(x^3+1)\left[3x^3-3x+2x^3+2\right] \color{blue}{\text{ (Distribute inside brackets)}}\\=x(x^2-1)(x^3+1)(5x^3-3x+2) \color{blue}{\text{ (Simplify)}}$$
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