
已知x-y=5 (1)求代数式3-x+y的值 (2)求代数式(x-y)平方-2x+2y 5
2个回答
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x-y=5
3-x+y
=3-(x-y)
=3-5
=-2
(x-y)²-2x+2y
=(x-y)²-2(x-y)
=5²-2×5
=25-10
=15
3-x+y
=3-(x-y)
=3-5
=-2
(x-y)²-2x+2y
=(x-y)²-2(x-y)
=5²-2×5
=25-10
=15
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