Question

1、因式分解：a^2(a-b)+(b-a) 已知x+y=2,xy=2/3,求：(x-y)^2

Answer 1

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

=(a^2-1)(a-b)

=(a+1)(a-1)(a-b)

2.(x-y)^2

=(x+y)^2-4xy

=4-8/3

=4/3