a+2b+(4b^2/a-2b)-(4a^2b/a^2-4b^2)=(a+2b)(a-2b)/(a-2b)+4b²/(a-2b)-4a²b/(a+2b)(a-2b)=[(a+2b)(a-2b)+4b²]/(a-2b)-4a²b/(a+2b)(a-2b)=a²/(a-2b)-4a²b/(a+2b)(a-2b)=a²(a+2b)/(...