Question

计算 （1）[(x+2)(x-2)]^2 （2）(x+2y-3)(x-2y+3)(3)(x+y)^2(x-y)^2-(x

Answer 1

计算 （1）[(x+2)(x-2)]^2 =[x^2-4]^2=x^4-8x^2+16

（2）(x+2y-3)(x-2y+3)=[x+(2y-3)][x-(2y-3)]=x^2-(2y-3)^2=x^2-4y^2+12y-9

(3)(x+y)^2(x-y)^2-(x-y)(x+y)(x^2+y^2)

=(x+y)(x-y)[(x+y)(x-y)-x^2-y^2]

=(x^2-y^2)*(-2y^2)

=2y^4-2x^2y^2