(a/3a+6)-(5/a²+4a+4)怎么算,
问题描述：
(a/3a+6)-(5/a²+4a+4)怎么算,
答
a/(3a+6)-5/(a²+4a+4)=a/[3(a+2)]-5/(a+2)²=a(a+2)/[3(a+2)²]-5*3/[3(a+2)²]=[a(a+2)-15]/[3(a+2)²]=[a²+2a-15]/[3(a+2)²]=(a+5)(a-3)/[3(a+2)²]