1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    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!

Homework Help: Equation query

  1. Jan 1, 2015 #1
    1. The problem statement, all variables and given/known data
    (3.4)^2x+3 = 8.5. Solve for x

    2. Relevant equations

    3. The attempt at a solution
    3.4^2x = 8.5/3.4^3 ( divide the equation by 3.4^3. This bit i am not sure about)

    2xlog3.4 = log (8.5/3.4^3

    x = log (8.5)- 3log(3.4) / 2 log (3.4)

    x = -0.626

    This seems to work out when i plug it in to the original equation.
    Is there an insert equation icon on the template. Can`t find it!
  2. jcsd
  3. Jan 2, 2015 #2


    Staff: Mentor

    I think you meant to say:

    (3.4)^(2x+3) = 8.5. Solve for x.

    Right? If not you need to edit your post to fix it.

    What do you mean by "an insert equation icon"?
  4. Jan 2, 2015 #3
    Looked at the question again and I have wrote it correctly. 3.4 is in parentheses. Not sure why this is so.

    An equation icon makes my equations look neater if you know what I mean!
  5. Jan 2, 2015 #4


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Are you saying that the original looks exactly like that, using the caret symbol instead of a superscript? Seems unlikely, so what you have posted is probably a rendition. But what you posted is equivalent to 3.42x+3. If you meant 3.42x+3 then you can write it as 3.4^(2x+3). And I feel it is a little simpler to take logs first then solve 2x+3 = log(8.5)/log(3.4).
  6. Jan 2, 2015 #5
    Apologies jedishrfu, I have wrote it down wrong. Thanks haruspex, I should have used parentheses after the caret symbol. You live and learn!!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted