How do you integrate e^(-x)dxe−xdx?
1 Answer
Apr 26, 2016
Explanation:
We will use the following integral rule:
inte^udu=e^u+C∫eudu=eu+C
Thus, to integrate
inte^-xdx∫e−xdx
We set
color(red)(u=-x)" "=>" "(du)/dx=-1" "=>" "color(blue)(du=-dx)u=−x ⇒ dudx=−1 ⇒ du=−dx
Since we have only
inte^-xdx=-inte^color(red)(-x)color(blue)((-1)dx)=-inte^color(red)ucolor(blue)(du)∫e−xdx=−∫e−x(−1)dx=−∫eudu
This is the rule we knew originally. Don't forget that the integral is multiplied by
-inte^udu=-e^u+C=barul|color(white)(a/a)-e^-x+Ccolor(white)(a/a)|