00:01
So with this definite integral problem, i'm going to use u substitution to explain it.
00:09
And you might have an instructor that's got a faster way of doing this, which is totally fine.
00:15
But my students need to see this u substitution.
00:19
And i'm letting u equal the exponent.
00:22
So the derivative of that is negative 2x dx.
00:26
And it might help somebody, so i might as well show it, that dx is equal to negative 1 over 2x.
00:32
And the reason why i bring that to your attention is then this integral i can rewrite as i'm going to leave x there for a second we have e to the u power because negative x squared is equal to you i'm going to replace d x with what's equal to that and that's this negative 1 over 2x d u the reason why i'm showing you that is these x will go away so we're looking at negative 1 half e to the u to you.
01:03
Now you also have to change your bounds because this is in terms of x.
01:07
Well, it's zero squared is still zero.
01:12
We have to change it in terms of u...
