【若x+y=6,xy=-8,求代数式(x+y-z)^2+(x+y-z)(x+y+z)-2·z(】

【若x+y=6,xy=-8,求代数式(x+y-z)^2+(x+y-z)(x+y+z)-2·z(】

(x+y-z)²+(x+y-z)(x+y+z)-2z(x-y)=[(x+y)-z]²+[(x+y)-z][(x+y)+z]-2z(x-y)=(x+y)²-2z(x+y)+z²+(x+y)²-z²-2z(x-y)=-2z[(x+y)+(x-y)]=-2z(2x)=-4xz应该是式子错了!没有答案!很高兴为您解答,祝你学习进步!【the 1900】团队为您答题.有不明白的可以追问!如果您认可我的回答.请点击下面的【选为满意回答】按钮.如果有其他问题请另发或点击向我求助,答题不易,请谅解,谢======以下答案可供参考======供参考答案1:(x-y)²=x²-2xy+y²=x²+2xy+y²-4xy=(x+y)²-4xy=36-4*(-8)=36+32=68=4*17x-y=±2√17(x+y-z)²+(x+y-z)(x+y+z)-2z(x-y)=(6-z)²+(6-z)(6+z)-2z(x-y)=36-2z+z²+36-z²-2z(x-y)=72-2z-2z(x-y)=72-2z(1±2√17)不能化简, 题目应该有错

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