已知a+b=6ab=8求a^3b+ab^3和3a^ - 知识问答

已知a+b=6ab=8求a^3b+ab^3和3a^2-6ab+3b^2

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a^3b+ab^3
=ab(a^2+b^2)
=ab[(a+b)^2-2ab]
=8x(6^2-2x8)
=160
3a^2-6ab+3b^2
=3(a-b)^2
=3[(a+b)^2-4ab]
=3(6^2-4x8)
=12

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