7/(m2+3m+2)-4/(m2+4m+3)+2/(m2+5m+6)怎么计算
问题描述：
7/(m2+3m+2)-4/(m2+4m+3)+2/(m2+5m+6)怎么计算
答
原式=7/(m+1)(m+2)-4/(m+1)(m+3)+2/(m+2)(m+3)=(7m+21-4m-8+2m+2)/(m+1)(m+2)(m+3)=(5m+15)/(m+1)(m+2)(m+3)=5/(m+1)(m+2)