((2a+2b)分之（a-b))-（（a方-b方）分之（a方+b方）））=(a-b)/[2*(a+b)] -(a^2+b^2)/[(a+b)(a-b)]通分,得：=[(a-b)(a-b)-2*(a^2+b^2)]/[2*(a+b)(a-b)]=[-(a+b)^2]/[2*(a+b)(a-b)]=-(a+b)/2(a-b)希望我的回答让你满...