∫ e − x d x , u = − x ∫ e − x d x {\displaystyle {\begin{aligned}&\int {e^{-x}}dx\\[2ex],u=-x&\int {e^{-x}}dx\\[2ex]\end{aligned}}}
![{\displaystyle {\begin{aligned}&\int {e^{-x}}dx\\[2ex],u=-x&\int {e^{-x}}dx\\[2ex]\end{aligned}}}](https://en.wikipedia.org/api/rest_v1/media/math/render/svg/29c4aa173a8bce4ba0cd517b2a0ee0cdb2de2422)