(x-y+z)(x+y+z)等于多少?

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(x-y+z)(x+y+z)等于多少?(x-y+z)(x+y+z)等于多少?(x-y+z)(x+y+z)等于多少?(x-y+z)(x+y+z)=[(x+z)-y][(x+z)+y]=(x+z)

(x-y+z)(x+y+z)等于多少?
(x-y+z)(x+y+z)等于多少?

(x-y+z)(x+y+z)等于多少?
(x-y+z)(x+y+z)
=[(x+z)-y][(x+z)+y]
=(x+z)²-y²
=x²+z²-y²+2xz

把x+z看作一个整体,这个式子就是个平方差,即(x+z)^2-y^2=x^2-y^2+z^2+2xz