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

题目详情
(x+2y-z)(x-2y+z)-(x+2y+z)^2
▼优质解答
答案和解析
(x+2y-z)(x-2y+z)-(x+2y+z)^2
=[x+(2y-z)][x-(2y-z)]-[x+(2y+z)]²
=x²-(2y-z)²-[x²+2x(2y+z)+(2y+z)²]
=x²-(4y²-4yz+z²)-x²-4xy-2xz-(4y²+4yz+z²)
=-8y²-4xy-2xz-2z²