Question 637682
solve for x 

     lnx + ln(x+7)=2
------------------------
Adding logs --> multiplying
ln(x*(x+7)) = 2
{{{x*(x+7) = e^2}}}
{{{x^2 + 7x - e^2 = 0}}}
*[invoke solve_quadratic_equation 1,7,e^2]
===============
x = (-7/2) ± sqrt(49 + 4e^2)/2
------------
e and e^2 are just constants.