Results 1 to 9 of 9

Math Help - Division revisited.

  1. #1
    Junior Member
    Joined
    Mar 2007
    Posts
    45

    Division revisited.

    I have a really stupid question. How do you add fractions, say, 1/2 +1/3 without doing it the long way. Now that I am doing complex fractions, the elementary way doesn't work. Thanks so much!!

    JT
    Follow Math Help Forum on Facebook and Google+

  2. #2
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by Mathfailure View Post
    I have a really stupid question. How do you add fractions, say, 1/2 +1/3 without doing it the long way. Now that I am doing complex fractions, the elementary way doesn't work. Thanks so much!!

    JT
    What do you call the long way?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Mar 2007
    Posts
    45
    Quote Originally Posted by Jhevon View Post
    What do you call the long way?


    It won't let me write it out, so I'll try to explain it. It's where you take the two fractions, find the LCD, see how many times the dedominator goes into the LCD, times it by the numerator, and finally add the two numerators... If this is confusing you could just show me both ways or all the ways and I'd be more than happy. Thanks
    Follow Math Help Forum on Facebook and Google+

  4. #4
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by Mathfailure View Post
    1/3 = _6_
    24
    - - = _1_
    1/8 = _3_ 8
    24
    Ok, so i'm guessing the alignment is off here, i dont get what you're saying.

    1/2 + 1/3

    obviously the LCM here is 6, so we can do the following:

    ....1..........1
    ...---...+...---
    ....2..........3

    ....3(1) + 2(1)
    = -------------
    ..........6
    .....5
    = ----
    .....6


    OR

    ....1..........1
    ...---...+...---
    ....2..........3

    = ....1.....3..........1.....2
    ......---*---...+...---*---
    .......2.....3..........3.....2

    ......3..........2
    =...---...+...---
    ......6..........6

    .....5
    = ----
    .....6
    Follow Math Help Forum on Facebook and Google+

  5. #5
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    There is another way still:

    you multiply the denominators to get the new denominators, and to get the new numerators, cross multiply opposing numerators and denominators. that is, to get the first numerator, multiply the first numerator in the first original function by the denominator in the second original fraction, then replace the sign, and multiply the second numerator in the second fraction by the denominator of the first fraction, here's a pic:
    Attached Thumbnails Attached Thumbnails Division revisited.-frac.jpg  
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Junior Member
    Joined
    Mar 2007
    Posts
    45
    Quote Originally Posted by Jhevon View Post
    There is another way still:

    you multiply the denominators to get the new denominators, and to get the new numerators, cross multiply opposing numerators and denominators. that is, to get the first numerator, multiply the first numerator in the first original function by the denominator in the second original fraction, then replace the sign, and multiply the second numerator in the second fraction by the denominator of the first fraction, here's a pic:

    Thanks so much! For some reason we only learned the 2nd way that you pointed out back in like 3rd grade.. Thanks again!
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Super Member
    Joined
    Oct 2006
    Posts
    679
    Awards
    1

    Re:

    Re:
    Attached Thumbnails Attached Thumbnails Division revisited.-adding-fractions.gif  
    Follow Math Help Forum on Facebook and Google+

  8. #8
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by qbkr21 View Post
    Re:
    what does that -+- in the middle mean?
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Super Member
    Joined
    Oct 2006
    Posts
    679
    Awards
    1

    Re:

    Its kind of like a code: Multiply the denominators, then just as you stated in your previous post diagonally cross multiply each of the corresponding numerators and denominators
    Attached Thumbnails Attached Thumbnails Division revisited.-adding-fractions-2.gif  
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. business plan revisited.
    Posted in the Algebra Forum
    Replies: 0
    Last Post: April 24th 2010, 11:48 AM
  2. Polynomial division vs synthetic division
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 9th 2009, 05:49 AM
  3. Mean Value Theorem Revisited!
    Posted in the Calculus Forum
    Replies: 2
    Last Post: December 30th 2008, 09:20 AM
  4. stationary points revisited
    Posted in the Calculus Forum
    Replies: 7
    Last Post: May 5th 2008, 08:40 AM
  5. Area of Circle Revisited
    Posted in the Calculus Forum
    Replies: 1
    Last Post: June 28th 2006, 08:02 PM

Search Tags


/mathhelpforum @mathhelpforum