x²/(x+2) - x+2
=x²/(x+2) -(x-2)
=[x²-(x+2)(x-2)]/(x+2)
=[x²-(x²-4)]/(x+2)
=4/(x+2)再来一题好么？？。12/m的平方-9+2/3-m12/(m²-9） + 2/(3-m) =12/(m²-9） - 2/(m-3) =[12- 2(m+3)]/(m²-9） =（6-2m)/(m²-9） =2(3-m)/[(m+3)(m-3)] =-2/(m+3)