x的3次方y的m-1次方*x的n+m次方y的2n+2次方=x的9次方y的9次方,则4m-3n的值是?

题目

x的3次方y的m-1次方*x的n+m次方y的2n+2次方=x的9次方y的9次方,则4m-3n的值是?
A.8
B.9
C.10
D.7
请尽快,

答案

x^3y^(m-1)x^(n+m)y^(2n+2)
=x^(3+n+m)y^(m-1+2n+2)
=x^(m+n+3)y^(m+2n+1)
=x^9y^9
m+n+3=9
m+2n+1=9
解得
m=4 n=2
4m-3n=16-6=10
选C.