∫ e − x d x , u = − x u = − x d u = − d x ∫ e − x d x = = − ∫ e u d u = = − e u d u = = − e − x + C {\displaystyle {\begin{aligned}&\int {e^{-x}}dx,u=-x\\[2ex]&u=-x\\[2ex]&du=-dx\\[2ex]&\int {e^{-x}}dx=&=-\int {e^{u}}du=&=-e^{u}du=&=-e^{-x}+C\end{aligned}}}
![{\displaystyle {\begin{aligned}&\int {e^{-x}}dx,u=-x\\[2ex]&u=-x\\[2ex]&du=-dx\\[2ex]&\int {e^{-x}}dx=&=-\int {e^{u}}du=&=-e^{u}du=&=-e^{-x}+C\end{aligned}}}](https://en.wikipedia.org/api/rest_v1/media/math/render/svg/45a947a901f4dc9aa7b5261bdfe562ec6afed34d)