Question

已知9m^2-6mn+n^2=0,则分式m+3n／2n-3m的值是

Answer 1

9m^2-6mn+n^2

=(3m-n)^2=0

得3m-n=0 n=3m

若m,n均不等于0 则

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

=(m+9m)/(6m-3m)

=10m/3m

=10/3

若m=n=0则无解.