Math problem?

Question

I spent away too much time trying to figure that one out . Can I get a clue or something please
Problem:
logx + log(x-9) = 1

Answer 1

Recall that log(a) + log(b) = log(a*b):

log(x) + log(x-9) = 1
log[x(x - 9)] = 1

What base are your logs in?

Suppose the base is b. Then exponentiate both sides of the equation, using b as the base, and use the fact that b^(log(t)) = t (where the log is to base b):

b^(log[x(x - 9)]) = b^1
x(x - 9) = b
x² - 9x - b = 0

Put in the correct value for b and solve for x.