Question

先化简再求值，{(-3mn)的平方×m的3次方-2m的平方×（3mn的平方）的3次方×2分之1n}÷（-3m平方n)的平方

要过程
m=-3，n=-1，求m，n的值

Answer 1

解：
原式
=[(-3mn)^2*m^3-2m^2*(3mn^2)^3*n/2]÷(-3m^2n)^2
=(9m^2n^2*m^3-2m^2*27m^3n^6*n/2)/(9m^4n^2)
=9m^5n^2/(9m^4n^2)-27m^5n^7/(9m^4n^2)
=m-3mn^5
=-3-3*(-3)*(-1)^5
=-3-9
=-12

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追问

=(9m^2n^2*m^3-2m^2*27m^3n^6*n/2)/(9m^4n^2)
=9m^5n^2/(9m^4n^2)-27m^5n^7/(9m^4n^2)
这两步什么意思

追答

=(9m^2n^2*m^3-2m^2*27m^3n^6*n/2)/(9m^4n^2)

=(9m^2n^2*m^3-2m^2*27m^3n^6*n/2)*1/(9m^4n^2)

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