Question 704682: ln(x)+ln(x-8)=5
I'm supposed to solve for x and I'm lost. I did it the way I thought it should be done but I got it wrong. Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website! ln(x)+ln(x-8)=5
ln((x)(x-8)) = 5
(x)(x-8) = e^5
x^2-8 = e^5
x^2-8x = e^5
x^2-8x-e^5 = 0
Solving using the "quadratic formula" yields:
x = {16.82, -8.82}
Since you can't take the ln of a negative number, the -8.82 is an extraneous solution. Throw it out leaving:
x = 16.82
.
Details of quadratic follows:
