Question

要使关于x,y的多项式my的3次方+3nx的2次方y+2y的3次方-x的2次方y+y不含三次项,求2m+3n的值?

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Answer 1

∵y^3、x^2y的系数为零
∴ m+2=0、3n-1=0 => m=-2、n=1/3
∴ 2m+3n=2*(-2)+3*(1/3)=-4+1=-3

追问

太慢了

Answer 2

m+2=0、3n-1=0 => m=-2、n=1/3
∴ 2m+3n=2*(-2)+3*(1/3)=-4+1=-3😃

Answer 3

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