Question

How do you evaluate the integral `int e^-xdx` from 0 to `oo`?

Answer 1

1

Explanation:

`int_0^oo e^-x \ dx`

`= int_0^oo -d/dx (e^-x) \ dx`

`= int_oo^0 d/dx (e^-x) \ dx`

`= [ e^-x ]_oo^0`

`=1 - 0 = 1`