Question

几道恒等变形题,1、(x-y-m+n)(n+m-x-y)2、(x+2y)(x-2y)(x^4-8x^2y^2+16y^4

Answer 1

[(n-y)+(x-m)][(n-y)-(x-m)]=(n-y)²-(x-m)²

(x^2-4y^2)(x^2-4y^2)²=(x^2-4y^2)³

第三个你看看是不是（4y-x）?