Let f(x) = (x - 1)/(x + 1). Compute f(f(f(2))).
f(x) = (x - 1) / (x + 1)
f(2) = (2 - x1 / (2 + 1) = 1/3
f( f(2) ) = f( 1/3 ) = (1/3 - 1) /(1/3 + 1) = -2/3 / 4/3 = -1/2
f( f ( f(2) ) ) = f( f( 1/3) ) = f( -1/2 ) = (-1/2 - 1) / (-1/2 + 1) = (-3/2) / (1/2) = -3