# Definite integral Problem 2

Calculus Level 4

$\large \int_{1}^{16} \tan^{-1} \sqrt{\sqrt x - 1} \, dx$

Given that the integral above is equal to $$a \pi - 2\sqrt b$$, where $$a$$ and $$b$$ are rational numbers, find the value of $$a\times b$$.

×