How do you solve #2 Log (x+7) = Log 9#? Precalculus Solving Exponential and Logarithmic Equations Logarithmic Models 1 Answer Özgür Özer Dec 3, 2015 #x=-4# Explanation: #2*log(x+7)=log9# #=>1/2*2*log(x+7)=1/2*log9# #=>log(x+7)=log(9^(1/2))# (the logarithm of a second root is the logarithm of the number divided by 2) #=>log(x+7)=log3# #=>x+7=10^log3# Add -7 to both sides: #x+7-7=3-7# #=>x=-4# 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 2093 views around the world You can reuse this answer Creative Commons License