已知x+y=17,xy=60,求x^2+y^2及(x-y)^2的值
要过程,谢谢
人气:338 ℃ 时间:2019-12-05 05:38:26
解答
x^2+y^2
=x²+2xy+y²-2xy
=(x+y)²-2xy
=17²-2×60
=289-120
=169
(x-y)²
=x²-2xy+y²
=169-2×60
=49
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