Question

已知m+n=3，mn=2/3，求m^3n-m^2n^2+mn^3的值。

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Answer 1

m^3n-m^2n^2+mn^3=mn（m^2-mn+n^2)=mn(m^2+2mn+n^2-3mn)=mn[(m+n)^2-3mn]=2/3×（3^2-3×2/3）=14/3