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x^3+y^3+z^3-xyz如何分解因式

题目详情
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答案和解析
x³+y³+z³-3xyz
=(x³+3x²y+3xy²+y³+z³)-(3xyz+3x²y+3xy²)
=[(x+y)³+z³]-3xy(x+y+z)
=(x+y+z)(x²+y²+2xy-xz-yz+z²)-3xy(x+y+z)
=(x+y+z)(x²+y²+z²+2xy-3xy-xz-yz)
=(x+y+z)(x²+y²+z²-xy-yz-xz)