How do you evaluate the expression #log_9 243#? Precalculus Properties of Logarithmic Functions Logarithm-- Inverse of an Exponential Function 1 Answer sjc Nov 4, 2016 #log_(9)243=5/2# Explanation: #log_ab=c=>a^c=b# #y=log_(9)243=>9^y=243# recognising that #243# is a power of #3# # 3^5=243# and #9^(1/2)=3# we have# (9^(1/2))^5=243# #:.9^(5/2)=243# #y=5/2# Answer link Related questions What is a logarithm? What are common mistakes students make with logarithms? How can a logarithmic equation be solved by graphing? How can I calculate a logarithm without a calculator? How can logarithms be used to solve exponential equations? How do logarithmic functions work? What is the logarithm of a negative number? What is the logarithm of zero? How do I find the logarithm #log_(1/4) 1/64#? How do I find the logarithm #log_(2/3)(8/27)#? See all questions in Logarithm-- Inverse of an Exponential Function Impact of this question 4070 views around the world You can reuse this answer Creative Commons License