m-2/n=2 2m+3n=12 要x

2x+n/m=m/n-(m/n+n/m)x（m+n不等于0） 计算：1.[(m+n)(n-m)-(m+n)^2+3m(m+n)]除以（-2M),其中m=-4,n=2 2.(x+y)( 已知3m=2n,则m/(m+n)+n/(m-n)-n^2/(m^2-n^2)=? 已知m/n=5、,求（m/（m+n）)+(m/(m-n))-(n^2/(m^3-n^2)) 若(m-2n)/(2m+n)=3,则[3(m-2n)/(2m+n)-(m-2n)/[2(2m+n)] - {9(m-2n 集合M={X=3m+1,m∈N*},N={y/y=5n+2,n∈N*},则M∩N=? 已知x^m=3,x^n=6 求 x^m-n,x^3m-2n的值 已知x^m=2,x^n=3(m、n是正整数),求:(1)x^2m=3n;(2)x^2m+x^3n. 已知x^m=2,x^n=5.(1)x^m+n、x^m-n的值；（2）求x^3m-2n的值 已知,单项式M,N满足2x(M+3x)=6x^2y^2+N,求M,N. 已知单项式M、N满足2x(M+3x)=6x^2y^2+N,求M、N. 已知单项式M,N满足3x(M-5x)=6x^2y^3+N,求M,N