How do you calculate #Log_7 (42 )#? Precalculus Properties of Logarithmic Functions Common Logs 1 Answer Kalyanam S. May 20, 2018 #color(pink)(=> 1.9208# Explanation: #log_7 42# As per base change rule, #log_b a = log_c a / log_c b# #log_7 42 = log_(10) 42 / log_(10) 7# #log (mn) = log m + log n# #:. => (log 7 + log 6) / log 7# #=> log 7 / log 7 + log 6 / log 7# }=> 1 + log 6 / log 7# #=> 1 + (0.7782) / (0.8451)# #color(pink)(=> 1.9208# Answer link Related questions What is the common logarithm of 10? How do I find the common logarithm of a number? What is a common logarithm or common log? What are common mistakes students make with common log? How do I find the common logarithm of 589,000? How do I find the number whose common logarithm is 2.6025? What is the common logarithm of 54.29? What is the value of the common logarithm log 10,000? What is #log_10 10#? How do I work in #log_10# in Excel? See all questions in Common Logs Impact of this question 2220 views around the world You can reuse this answer Creative Commons License