\input amstex f^{n+1}(x)=f(f^n (x))=f\left(\frac{x}{\sqrt{1+nx^2}\right)=\dfrac{\dfrac{x}{\sqrt{1+nx^2}}}{\sqrt{1+\dfrac{x^2}{1+nx^2}}}=\text{srediti izraz}=\frac{x}{\sqrt{1+(n+1)x^2}}