1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Math: log question-solving for x.

  1. Dec 16, 2009 #1
    1. The problem statement, all variables and given/known data
    Solve: log(sub6)x+log(sub6)(x-5) = 2

    2. Relevant equations


    3. The attempt at a solution

    i multiplied the second log out and got:
    log(sub6)x+log(sub6)x-log(sub6)5 = 2
    then i put the x's on one side and the numbers on the other.
    2(log(sub6)x) = 2+log(sub6)5

    but i have no idea how to go from there. or maybe i multiplied it out wrong?
  2. jcsd
  3. Dec 16, 2009 #2


    User Avatar
    Homework Helper

    Instead of doing all of that use this rule


    and then use the fact that logAa=n ⇒ a=An
  4. Dec 16, 2009 #3
    Try to understand each steps that i proceed.

    Attached Files:

    • 1.bmp
      File size:
      266.1 KB
  5. Dec 16, 2009 #4
    Ah! I see now, thank you both so much!
  6. Dec 16, 2009 #5


    Staff: Mentor

    Remember that from your original equation x has to be positive and x has to be greater than 5 (which together mean that x > 5). Otherwise one of the terms in your original equation will be undefined.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook