б) = (((4ab+(a-b)²)/2(a+b)(a-b)) *2a/(a+b) -b/(a-b) =
((a+b)²/2(a+b)(a-b)) *2a/(a+b) -b/(a-b) =a/(a-b) -b/(a-b) =(a-b)/(a-b) =1
--------4ab+(a-b)² =4ab +a²-2ab+b² =a²+2ab +b² =(a+b)² ---------------
в) = ( (4a+(a-1)²)/(a-1)(a+1) ) *2a/(a+1) - (a(a+1)+a)/(a² -1)=
((a+1)²/(a-1)(a+1)) *2a/(a+1) - (a² +2a)/(a² -1) =2a/(a-1) - (a² +2a)/(a² -1) =
( 2a(a+1) -(a²+2a) )/(a² -1) =a²(a² -1)