Question

已知a+b=1,ab=-3,求a^2b+ab^2和2a^3b+2ab^3的值,

Answer 1

a^2b+ab^2=ab(a+b)=-3*1=-3

2a^3b+2ab^3=2ab(a^2+b^2)=2ab(a^2+b^2+2ab-2ab)=2ab[(a+b)^2-2ab]=2*(-3)[1-2(-3)]=-42