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已知x2-xy=60,xy-y2=40,求代数式x2-y2和x2-2xy+y2的值.
人气:219 ℃ 时间:2019-08-22 15:05:57
解答
∵x2-xy=60,xy-y2=40,
∴x2-y2=(x2-xy)+(xy-y2)=100.
x2-2xy+y2=(x2-xy)-(xy-y2)=20.
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