What is the natural log of a? The natural log, the natural log of a is the power you need to raise e to to get to a. So if you actually raise e to that power, if you raise e to the power you need to raise e to to get to a, well, then you're just going to get to a. So really think about this. Don't just accept this as a leap of faith. It should make sense to you, and it just comes out of really what a logarithm is. And so we can replace a with this whole expression here.