当3m=2n时,分式m/(m+n)+n/(m-n)-n^2 /(m^2-n^2)=?_数学解答

当3m=2n时,分式m/(m+n)+n/(m-n)-n^2 /(m^2-n^2)=?

人气：477 ℃　时间：2020-04-16 04:37:09

解答

m/(m+n)+n/(m-n)-n^2 /(m^2-n^2)
=[m(m-n)+n(m+n)-n^2]/(m^2-n^2)
=m^2/(m^2-n^2)
=1/(1-(n/m)^2)
=1/(1-(3/2)^2)
=4/(4-9)
=-4/5