00:01
Sometimes what helps me is to look at what the derivative of 5 to the negative 2x power is.
00:07
So hopefully you have some practice with this that you would get natural log of 5 times 5 to the negative 2x because you leave that piece along times the derivative of negative 2x which would be negative 2.
00:21
And the reason why i like to go through that is if i'm going backwards, i need to divide by those pieces, the natural log of 5 and that negative 2.
00:29
And that's really how i would approach this problem for part a, where they give you the integral of 5 to the negative 2x.
00:38
And there's other ways of doing this.
00:39
It's just what i like to do.
00:42
So the answer would be 1 over negative, 2 and the natural log of 5, and then times 5 to the negative 2x.
00:52
And you can double check that's right, because if you take the derivative of this thing, you'll get back to this original problem...