SOLUTION: LOGx + LOG(x-15) = 2 Solve for x. Answer is 20 but I can not figure out how to get it. If it was log base 8 x + log base 8 (x-15) = 2 I can figure it out.

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: LOGx + LOG(x-15) = 2 Solve for x. Answer is 20 but I can not figure out how to get it. If it was log base 8 x + log base 8 (x-15) = 2 I can figure it out.       Log On


   

Question 893267: LOGx + LOG(x-15) = 2 Solve for x. Answer is 20 but I can not figure out how to get it. If it was log base 8 x + log base 8 (x-15) = 2 I can figure it out.

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
LOGx + LOG(x-15) = 2 Solve for x.
Adding logs is multiply
log%28%28x%28x-15%29%29%29+=+2
The exponent equiv
x(x-15) = 10^2
x^2 - 15x = 100
x^2 - 15x - 100 = 0
Factors to
(x - 20) (x + 5) = 0
only the positive solution is valid here
x = 20