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已知x+y=6,xy=-2,求(x^4-y^4)÷(6x-6y)的值.
人气:248 ℃ 时间:2020-06-25 12:17:21
解答
(x^4-y^4)÷(6x-6y)
=(x^2-y^2)(x^2+y^2)÷[(x+y)(x-y)]
=x^2+y^2
=(x+y)^2-2xy
=6^2-2×(-2)
=36+4
=40
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