Solve $LaTeX: \displaystyle \log_{20}(x + 3123)+\log_{20}(x + 1022) = 5$ .

Using logarithmic properties and expanding the argument gives $LaTeX: \displaystyle \log_{20}(x^{2} + 4145 x + 3191706)=5$ . Making both sides an exponent on the base gives $LaTeX: \displaystyle x^{2} + 4145 x + 3191706=20^{5}$ . Expanding and setting equal to zero gives $LaTeX: \displaystyle x^{2} + 4145 x - 8294=0$ . Factoring gives $LaTeX: \displaystyle \left(x - 2\right) \left(x + 4147\right)=0$ . Solving gives the two possible solutions $LaTeX: \displaystyle x = -4147$ and $LaTeX: \displaystyle x = 2$ . The domain of the original is $LaTeX: \displaystyle \left(-3123, \infty\right) \bigcap \left(-1022, \infty\right)=\left(-1022, \infty\right)$ . Checking if each possible solution is in the domain gives: $LaTeX: \displaystyle x = -4147$ is not a solution. $LaTeX: \displaystyle x=2$ is a solution.