Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: 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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook