Let f(x)=12x+1f(x) = \frac{1}{2x+1}f(x)=2x+11. If fn(x)f_n(x)fn(x) is the nnn-th iterate, find f2(x)f_2(x)f2(x).
\frac{1}{4x+2}
\frac{2x+1}{4x+3}
\frac{2x+1}{2}
\frac{x}{2x+1}