solving logarithm equations: log x + log (x+15)=2

[Red]

log x + log (x + 15) = 2

I know that you use the multiplication property but how do I factor the log?

 

[skeeter]

log x + log (x+15) = 2

log[x(x+15)] = 2

change to an exponential equation ...

x(x+15) = 10²

x² + 15x - 100 = 0

solve for x ... don't forget to check each solution in the original equation, one might not work.