Question

(а^2+1)(а-2)-а(а^2+1)

Answer 1

(a^2+1)(a-2) -a(a^2+1)

We perceive that a^2+1 is our common factor of the two terms. Therefore, we have:
(a^2+1)(a-2-a) (distributive property)
= (a^2+1)*(-2)
= -2a^2 -2

The final answer is -2a^2 -2~

Answer 2

Expand the brackets
a^3-2a^2+a-2 -a^3-a
Simplify
-(2a^2-2)