Answer
When $y = 1$, we can prove that the statement is false.
Work Step by Step
(a) $$log(x + y) = log(x) + log(y)$$ $$log(x + 1) = log(x) + log(1)$$ $$log(x+1) = log(x) + 0$$ $$log(x + 1) \neq log(x)$$
(b) $log(x+1)$ is the blue line; $log(x)$ is the green line.
