a) Find $\tan\left( \sin^{-1}(\frac {2}{5}) + \cos^{-1}(\frac {1}{5})\right)$ =.

(Make sure your answer is an algebraic expression with square roots but without trigonometric or inverse trignometric functions.)

b) Express in terms of $x$: $\sin\left( 2 \tan^{-1}(x)\right)$ = .