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: This should be easy

  1. Aug 21, 2008 #1
    I'm certain I'm missing something obvious .. again.

    I'm having trouble solving the following (using a pen and paper approach)

    [tex] \frac{ 3^{12} - 3^{10} }{ 3^{11} + 3^{10} } [/tex]

    I've tried logarithms (I've only covered those with base 10 so far, so any log_n approach is disqualified), messing around with the exponents, roots and factoring, but I cant seem to find a way to do this without actually calculating the individual values.

    Enlighten me, please.

    Last edited: Aug 21, 2008
  2. jcsd
  3. Aug 21, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Divide numerator and denominator by 3^10.
  4. Aug 21, 2008 #3


    User Avatar
    Science Advisor

    Or (same thing really) factor out a 310: 311= 310*3 and 312= 310*9
    [tex]\frac{3^{12}- 3^{10}}{3^{11}- 3^{10}}= \frac{3^{10}(9- 1)}{3^{10}(3- 1)}[/tex]
  5. Aug 21, 2008 #4
    aaah, sweet relief.

    thank you.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook