2m-3x       x+6m --------- +   -------- x^2-m^2    m^2-x^2

(2m-3x)/(x-m)(x+m)+ (x+6m)/(m-x)(m+x)=-(2m-3x)/(m-x)(m+x)+(x+6m)/(m-x)(m+x)=-2m+3x+x+6m=4x+4m=4(x+m)