Выражение! (a-1/a+1-a/a-1)*a+1/1-3a

(a/(a-1)+1):(1-3a^2/(1-a^2)==((a+a+1)/(a+1)):((1-a^2-3a^2)/(1-a^2)==((2a+1)/(a+1)) :((1-4a^2)/(1-a^2))==((2a+1)/(a+1)) : ((4a^2-1)/(a^2-1))==((2a+1)(a^2-1))/((a+1)(4a^2-1))==((2a+1)(a-a)(a+1))/((a+1)(2a-1)(2a+1))==(a-1)/(2a-1)