Answer
See explanations.
Work Step by Step
Step 1. $(\sqrt x+\sqrt {x-1})(\sqrt x-\sqrt {x-1})=(\sqrt x)^2-(\sqrt {x-1})^2=1$
Step 2. $log_a(\sqrt x+\sqrt {x-1})+log_a(\sqrt x-\sqrt {x-1})=log_a(\sqrt x+\sqrt {x-1})(\sqrt x-\sqrt {x-1})=log_a1=0$
