Question

Let f : $\R → \R$ be a bijective function such that for all x ∈ R, f(x) = $\sum\limits^{\infin}_{n=1}a_nx^n$ and $f^{-1}(x)=\sum\limits_{n=1}^{\infin}b_nx^n$, where f-1 is the inverse function of f. If a1 = 2 and a2 = 4, then b1 is equal to _________.

Answer 1

The correct answer is 0.49 to 0.51. (approx)