将下列多项式因式分解:(1) (z²-x²-y²)²-4x²y² (2) (a+b)²+

问题描述:

将下列多项式因式分解:(1) (z²-x²-y²)²-4x²y² (2) (a+b)²+

令A=x2、B=y2、C=z2
(C-A-B)2-4AB=A2+B2+C2-2CA-2AB-2BC+4AB
= A2+B2+C2-2CA+2AB-2BC=(A+B-C)2
=(x2+y2-z2)2

(z²-x²-y²)²-4x²y²
=(z^2-x^2-y^2-2xy)(z^2-x^2-y^2+2xy)
=[z^2-(x+y)^2][z^2-(x-y)^2]
=(z-x-y)(z+x+y)(z-x+y)(z+x-y) .

因式分 (1) (z²-x²-y²)²-4x²y² =(z^2-x^2-y^2-2xy)(z^2-x^2-y^2+2xy) =[z^2-(x+y)^2][z^2-(x-y)^2] =(z-x-y)(z+x+y)(z-x+y)(z+x-y) .