1、原式=((a-1)(a-1))/(a-1)-a^2/(a-1)=(a^2-2a+1-a^2)/(a-1)=(1-2a)/(a-1)2、原式=4/(a+2)+(（a+2）（a-2）)/(a+2)=(4+（a+2）（a-2）)/(a+2)=(4+a^2-2^2)/(a+2)=a^2/(a+2)3、原式=(x+3)/((x-3)(x+3))-(x-3)/((x-3)...