How do you solve # 10 log _ 10 (x+21) +log _ 10 (x)= 2#? Precalculus Properties of Logarithmic Functions Common Logs 1 Answer Cesareo R. Sep 2, 2016 #x approx 10^2/21^10# Explanation: # 10 log _ 10 (x+21) +log _ 10 (x)= 2# or #(x+21)^(10)x=10^2# Supposing #x = delta > 0# but very small, we will have #(delta + 21)^10 approx 21^10# so #21^10 delta approx 10^2# #delta approx 10^2/21^10# then the real solution is #x_0 approx 10^2/21^10# 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 1791 views around the world You can reuse this answer Creative Commons License