
已知(a-b)=5,ab=3,求(a+b)^2与3(a^2+b^2)的值
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(a+b)^2
=a^2+b^2+2ab
=(a^2+b^2-2ab)+4ab
=(a-b)^2+4ab
=5x5+4x3
=37
3(a^2+b^2)
=3(a-b)^2+6ab
=3x5x5+6x3
=93
=a^2+b^2+2ab
=(a^2+b^2-2ab)+4ab
=(a-b)^2+4ab
=5x5+4x3
=37
3(a^2+b^2)
=3(a-b)^2+6ab
=3x5x5+6x3
=93
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