Question

(a-x)(a+x^2)+(x-a)x^2

Answer 1

$(a-x)(a+x^2)+(x-a) \cdot x^2=(a-x)(a+x^2)-(a-x) \cdot x^2=\\(a-x)(a+x^2-x^2)=a(a-x)=a^2-ax.$