h ( x ) = ∫ 2 1 / x arctan ( t ) d t {\displaystyle h(x)=\int _{2}^{1/x}\arctan(t)dt}
h ′ ( x ) = − 1 x 2 ( arctan ( 1 x ) − 0 {\displaystyle h'(x)={\frac {-1}{x^{2}}}\left(\arctan({\frac {1}{x}}\right)-0}
