Results 1 to 4 of 4

Math Help - this might be simple... but i dont know

  1. #1
    Junior Member eah1010's Avatar
    Joined
    Nov 2005
    Posts
    28

    Unhappy this might be simple... but i dont know

    ok help.. this might sound super easy... but i cant seem to get it... i thought the answer was 1 but my teacher said it was wrong...


    2^29 - 2^28
    __________
    2
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Quick's Avatar
    Joined
    May 2006
    From
    New England
    Posts
    1,024
    Quote Originally Posted by eah1010 View Post
    ok help.. this might sound super easy... but i cant seem to get it... i thought the answer was 1 but my teacher said it was wrong...


    2^29 - 2^28
    __________
    2
    A big thing to watch out for is the fact that x^a-x^b does not equal x^(a-b)

    Now you have problem: (2^29-2^28)/2

    distribute: (2^29)/(2)-(2^28)/(2)

    divide: 2^28-2^27

    factor: (2^27)(2-1)

    subtract: (2^27)(1)

    therefore the answer is: 2^27
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Joined
    Oct 2005
    From
    Earth
    Posts
    1,599
    Well try testing smaller numbers to see why you can't just subtract.

    Let's try 2^3-2^2. Expanding out both terms gives you 8-4=4. Now let's factor this to see if that can make some sense. 2^3-2^2=2^2(2-1)=2(1)=2

    Apply this same technique to your problem.

    2^29-2^28=2^28(2-1)=2^28(1)=2^28

    And divide by two. So (2^28)/2=2^27
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member eah1010's Avatar
    Joined
    Nov 2005
    Posts
    28
    thank you so much! you guys rock!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. I dont get it
    Posted in the Algebra Forum
    Replies: 10
    Last Post: August 4th 2010, 07:49 AM
  2. Replies: 2
    Last Post: January 30th 2010, 03:56 AM
  3. I dont even know what this is called...
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: October 20th 2009, 05:54 AM
  4. I dont get this..i need help
    Posted in the Statistics Forum
    Replies: 3
    Last Post: May 1st 2009, 02:30 PM
  5. Help? i dont get it
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 7th 2009, 05:35 PM

Search Tags


/mathhelpforum @mathhelpforum