Question

若(m-2n)/(2m+n)=3,则[3(m-2n)/(2m+n)-(m-2n)/[2(2m+n)] - {9(m-2n

Answer 1

(m-2n)/(2m+n)=3

m-2n=6m+3n

5m+5n=0

m=-n

[3(m-2n)/(2m+n)-(m-2n)/[2(2m+n)] - {9(m-2n)/[4(2m+n)]}

=[3(-n-2n)/(-2n+n)-(-n-2n)/2(-2n+n)]-[9(-n-2n)/4(-2n+n)]

=(9-3/2)-27/4

=3/4