Consider the following problem:
I got $g'(1) = f'(1) = 2$, which is correct according to the expected answer. However, I get that $a$ can be any value, as it doesn't affect anything and $g$ is differentiable no matter what $a$ is (am I missing something here?). The expected answer is that $a$ must be $2$ however.
Can someone explain why $a$ needs to be $2$?