Solving log functions

1) log x + log(x-6) = log 7

2 answers

adding logs is same as multiplying the arguements.

LogA+LogB= log(AB)

log(x(x-6))=log7
take the antilog of each side.
x(x-6)=7
solve.
Note that
x^2 -6x -7 = 0
is easily factored.

There are two solutions that are integers. Only the positive root is allowed, however, since the log of a negative number is undefined.