计算: (x-2y+z)(x+2y+z)要过程,谢

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计算: (x-2y+z)(x+2y+z)要过程,谢

计算: (x-2y+z)(x+2y+z)要过程,谢
计算: (x-2y+z)(x+2y+z)要过程,谢

计算: (x-2y+z)(x+2y+z)要过程,谢
(x-2y+z)(x+2y+z)
=(x+z-2y)(x+z+2y)
=(x+z)²-(2y)²
=x²+2xz+z²-4y²

把前面两项看成一项

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

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

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

平方差公式的运用:(x+z-2y)(x+z+2y)=(x+z)²-(2y)²=x²+2xz+z²-4y²