Question

1.x(a-b)-y(b-a)+z(a-b)

Answer 1

1.x(a-b)-y(b-a)+z(a-b)

=x(a-b)+y(a-b)+z(a-b)

=(x+y+z)(a-b)

2.已知a+b=1,ab=-1/2,求a(a+b)(a-b)-a(a+b)^2

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

=a(a²-b²)-a(a²+2ab+b²)

=a(-b²-2ab-b²)

=a(-2b²-2ab)

=-2ab(a+b)

=-2*(-1/2)*1

=1