Solve $LaTeX: \displaystyle \log_{ 15 }(x + 18) + \log_{ 15 }(x + 18) = 2$

Using the product rule for logarithms gives $LaTeX: \displaystyle \log_{ 15 }(\left(x + 18\right)^{2})$ and rewriting in exponential form gives $LaTeX: \displaystyle \left(x + 18\right)^{2} = 225$ expanding and setting the equation equal to zero gives $LaTeX: \displaystyle x^{2} + 36 x + 99 = 0$ . Factoring gives $LaTeX: \displaystyle \left(x + 3\right) \left(x + 33\right)=0$ . This gives two possible solutions $LaTeX: \displaystyle x=-33$ or $LaTeX: \displaystyle x=-3$ . $LaTeX: \displaystyle x=-33$ is an extraneous solution. The only soution is $LaTeX: \displaystyle x=-3$ .