∫ cos ( t ) t d t = ∫ u {\displaystyle \int {\frac {\cos {({\sqrt {t}})}}{\sqrt {t}}}dt=\int {\sqrt {u}}}
u = u d u = 1 2 1 ( t ; d x 1 π d u = d x {\displaystyle {\begin{aligned}u&={\sqrt {u}}\\[2ex]du&={\frac {1}{2}}\ {\frac {1}{({\sqrt {t}}}};dx\\[2ex]{\frac {1}{\pi }}du&=dx\end{aligned}}}
![{\displaystyle {\begin{aligned}u&={\sqrt {u}}\\[2ex]du&={\frac {1}{2}}\ {\frac {1}{({\sqrt {t}}}};dx\\[2ex]{\frac {1}{\pi }}du&=dx\end{aligned}}}](https://en.wikipedia.org/api/rest_v1/media/math/render/svg/fb7291265f8c499f9969a5cf8044dba0f5a35510)