计算(x-y+z)的二次方减(x+y-z)的二次方

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计算(x-y+z)的二次方减(x+y-z)的二次方

计算(x-y+z)的二次方减(x+y-z)的二次方
计算(x-y+z)的二次方减(x+y-z)的二次方

计算(x-y+z)的二次方减(x+y-z)的二次方
(x-y+z)^2-(x+y-z)^2
=(x-y+z+x+y-z)(x-y+z-x-y+z)
=2x(2z-2y)
=4x(z-y)

用平方差计算

=[(x-y+z)+(x+y-z)][(x-y+z)-(x+y-z)]
=2x(-2y+2z)
=-4xy+4xz

(x-y+z)^2-(x+y-z)^2=(x-y+z+x+y-z)(x-y+z-x-y+z)=2x(2z-2y)=4x(z-y)

x-y+z=x-(y-z)
设y-z=m
则,原式可变为(x-m)的二次方减去(x+m)的二次方
展开分解计算后,得4xm
再把m代入,可得出答案

平方差公式得:2x(2z-2y)=4x(z-y)