(3) If f(x) = x^2 + 2x + 1, then (f^-1)'(4) =

Part II : Give the detailed calculation or proof process of the following questions. 2. Suppose that $$\{a_n\}$$ is a sequence $$a_1 = 1$$ and $$a_{n+1} = \sqrt{a_n + 2}$$, $$\forall n \in N$$. (1) $(8\%)$ Prove that $1 \leq a_{n} \leq 2$, and $a_{n} \leq a_{n+1}$, $\forall n \in N$.