I'm going through the following heat equation problem, and I understand how the solution is constructed except for one algebraic re-arrangement that I can't make sense of (and its probably really obvious) which is right at the start of the solution. I was hoping someone could enlighten me.
Solve on with IC's and BC's .
The example says:
Confused from here:
To the line above
From here I have no problems understanding and solving this problem.
This is probably embarrassingly simple, but I keep getting
and why is this equal to