How to expand and compute log(a + b)? [closed]
Solution 1:
In general, one doesn't expand out log(a + b); you just deal with it as is. That said, there are occasionally circumstances where it makes sense to use the following identity:
log(a + b) = log(a * (1 + b/a)) = log a + log(1 + b/a)
(In fact, this identity is often used when implementing log in math libraries).