How do you solve #ln x + ln 3x = 12#? Precalculus Solving Exponential and Logarithmic Equations Logarithmic Models 1 Answer Vinícius Ferraz Dec 6, 2015 #x = + sqrt(3)/3 e^6# Explanation: #ln (x * 3x) = 12# #x * 3x = e^12# #x^2 = 1/3 e^12# #x = ± sqrt(3)/3 e^6# But x > 0. Answer link Related questions What is a logarithmic model? How do I use a logarithmic model to solve applications? What is the advantage of a logarithmic model? How does the Richter scale measure magnitude? What is the range of the Richter scale? How do you solve #9^(x-4)=81#? How do you solve #logx+log(x+15)=2#? How do you solve the equation #2 log4(x + 7)-log4(16) = 2#? How do you solve #2 log x^4 = 16#? How do you solve #2+log_3(2x+5)-log_3x=4#? See all questions in Logarithmic Models Impact of this question 3556 views around the world You can reuse this answer Creative Commons License