2 log(x + a) = log(16a^6) where a is a positive constant. How do I find x in terms of a?

The left hand side of the equation can be rewritten as log(x+a)^2, using the power rule for logs. We can then simplify log(x+a)^2=log(16a^6) to (x+a)^2=16a^6. Taking the square root of both sides, we find x+a=4a^3. Finally, we can rearrange to find x=4a^3-a.