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m^2+2mn=384,3mn+2n^2=560,则2m^2+13mn+6n^2-438的值是
人气:487 ℃ 时间:2020-04-02 23:16:48
解答
m^2+2mn=384,3mn+2n^2=560
2m²+4mn=768 9mn+6n²=1680
2m²+4mn+9mn+6n²=768+1680
2m²+13mn+6n²=2448
∴2m²+13mn+6n²-438=2448-438=2010
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