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: Indice Problem

  1. Aug 14, 2010 #1
    1. The problem statement, all variables and given/known data
    Simplify: (2n+4 - 2 x 2n) / (2n+2 x 4)

    2. Relevant equations

    3. The attempt at a solution
    (2n+4 - 2n+1) / (2n+4)

    Unsure where to go from here, but the given answer is 7/8
    Thanks for any help
    Last edited: Aug 14, 2010
  2. jcsd
  3. Aug 14, 2010 #2


    User Avatar
    Science Advisor

    Please use parentheses! Is this
    [itex](2^{n+4} - 2^{n+ 1}) / (2^{n+2}(4))[/itex]
    or [itex]2^{n+4}- (2^{n+1}/2^{n+2})(4)[/itex]
    or [itex]2^{n+4}- (2^{n+1})/(2^{n+2}(4))[/itex]?

    Assuming it is the first, yes, the denominator will be [itex]2^{n+ 4}[/itex]. The numerator is [itex]2^{n+4}+ 2^{n+1}[/itex] which we can write as [itex]2^{n+1}2^3- 2^{n+1}=[/itex][itex] 8(2^{n+1})- 2^{n+1}=[/itex][itex] 2^{n+1}(8- 1)= 2^{n+1}(7)[/itex].

    Can you reduce

    Last edited by a moderator: Aug 15, 2010
  4. Aug 14, 2010 #3
    Thanks for replying and I've added some brackets (the question didn't have any). Wouldn't the numerator be [itex]2^{n+4}- 2^{n+1}[/itex]?
  5. Aug 14, 2010 #4


    Staff: Mentor

    Added a closing tex tag, and changed a leading itex tag to a tex tag.
    Sign error above that you corrected below. The numerator is 2n+4 - 2n+1.
  6. Aug 14, 2010 #5
    Thank you it makes sense now.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook