# \$f(f(x)) = 1 + x^2\$, then what is f(1)?

by Ziqin He   Last Updated August 14, 2019 06:20 AM

I get $$f(f(a)) = a^2 + 1 = f(f(-a))$$, and so $$f(a)^2 + 1 = f(a^2 + 1) = f(-a)^2 + 1$$, so $$f(a) = f(-a)$$ or $$f(a) = -f(-a)$$, but then I donot know what to do next. Thanks for any help.

Tags :

## Related Questions

Updated January 11, 2019 07:20 AM

Updated November 21, 2017 07:20 AM

Updated January 30, 2019 16:20 PM

Updated February 16, 2019 13:20 PM

Updated May 13, 2017 07:20 AM