3а/4а^2 -1 - а+1/2а^2+а
3а/(2а-1)(2а+1) - (а+1)/а(2а+1)=3а² - (а+1)(2а-1) / а(2а-1)(2а+1)=(а²-а+1) / а(2а+1)(2а-1)...