сократите дробь
12^(n+1) / ( 2^(2n-1) * 3^(n+3) )
12^(n+1) / ( 2^(2n-1) * 3^(n+3) ) = ( 12^n *12*2) / (2^(2n)*3^(n)*3^3) = (3^n*4^n*24)/(4^n*3^n*3^3) = 24/27 = 8/9