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若x-y=1,则x方-y方-2y-5=
人气:410 ℃ 时间:2020-06-14 21:48:03
解答
x方-y方-2y-5
=(x+y)(x-y)-2y-5
=(x+y)×1-2y-5
=x+y-2y-5
=x-y-5
=1-5
=-4
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