(m的2次方-6mn+9n的2次方)/(m-3n)-(4m的二次方-9n的二次方)/(2m-3n)

问题描述:

(m的2次方-6mn+9n的2次方)/(m-3n)-(4m的二次方-9n的二次方)/(2m-3n)

(m的2次方-6mn+9n的2次方)/(m-3n)-(4m的二次方-9n的二次方)/(2m-3n)
=(m+3n)^2/(m-3n)-(2m+3n)(2m-3n)/(2m-3n)
=m+3n-(2m+3n)
=-m