How do you solve #10^(-x+4) +7 = 5 # and find any extraneous solutions? Precalculus Properties of Logarithmic Functions Common Logs 1 Answer A. S. Adikesavan Jun 4, 2016 There is no real solution. Explanation: For #a > 0, a^n>0 and lim n to -oo# of # a^n = 0#. So, #10^(-x+4)>0#. Here, it is valued as #-2#. 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 1326 views around the world You can reuse this answer Creative Commons License