if f(x).f(1/x) = f(x) + f(1/x) then prove that f(x) = xⁿ+ 1

Hii
you can find out the value of f(x) and f(1/x) .
Multilply f(x) and f(1/x) and then add f(x) and f(1/x).
So both these values will be equal.

In this question.. It must be given that the function is a polynomial(which is indirectly given to be proved).. So take a general polynomial of degree n and then subsitute that in the given equation.. Then compare both sides coefficient then you will get the proof