log(-1) = 0

Theorem: log(-1) = 0
Proof:
a. log[(-1)^2] = 2 * log(-1)

On the other hand:
b. log[(-1)^2] = log(1) = 0

Combining a) and b) gives:
2* log(-1) = 0
Divide both sides by 2:
log(-1) = 0