h ( x ) = ∫ 2 1 / x arctan ( t ) d t {\displaystyle h(x)=\int _{2}^{1/x}\arctan(t)dt}
h ′ ( x ) = − 1 x 2 ( a r c t a n ( f r a c 1 x − 0 {\displaystyle h'(x)={\frac {-1}{x^{2}}}(arctan(frac{1}{x}-0}
