若a+3b=0,则[1-b/a+2b]÷a+2ab+b/a-4b=?

若a+3b=0,则[1-b/a+2b]÷a+2ab+b/a-4b=?
若a+3b=0,则[1-b/a+2b]÷a+2ab+b/a-4b=?

若a+3b=0,则[1-b/a+2b]÷a+2ab+b/a-4b=?
若a+3b=0,则[1-(b/a+2b)]÷[(a+2ab+b)/(a-4b)]=?a+3b=0 a=-3b 原式=[(a+2b-b)/(a+2b)]÷(a+b)^2/(a+2b)(a-2b) =(a+b)/(a+2b)×(a+2b)(a-2b)/(a+b)^2 =(a-2b)/(a+b) =(-3b-2b)/(-3b+b) =-5b/(-2b) =5/2