2a+6分之a+15-a^2+6a+9分之a^2-81除以a+3分之a-9
问题描述：
2a+6分之a+15-a^2+6a+9分之a^2-81除以a+3分之a-9
答
原式=[(a+15)/(2a+6)]-[(a²-81)/(a²+6a+9)]÷[(a-9)/(a+3)]=[(a+15)/(2a+6)]-[(a+9)(a-9)/(a+3)²]×[(a+3)/(a-9)]=[(a+15)/(2a+6)]-[(a+9)/(a+3)]={ (a+15)/[2(a+3)] }-{ 2(a+9)/[2(a+3)] }=[(a+15)-...