I am having trouble with this grade 12 pre-calc question that I am sure will be elementary to most of you. I understand most of it but I do not understand one of the steps.
These are the steps in my answer-key:
$ 4 = log_2x+log_2(x+6) $
$ 4 = log_2(x^2+6x) $
$ 2^4 = x^2+6x $
What happens to 4 to become $2^4$? Thanks!