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计算(x+y)的平方-(x的立方+y的立方)÷(x+y)
人气:480 ℃ 时间:2019-12-24 20:36:42
解答
(x+y)^2-(x^3+y^3)/(x+y)
=(x+y)^2-[(x+y)*(x^2-xy+y^2)]/(x+y) PS:x^3+y^3=(x+y)(x^2-xy+y^2)
=(x+y)^2-(x^2-xy+y^2)
=x^2+2xy+y^2-x^2+xy-y^2
=3xy
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