Results 1 to 10 of 10

Math Help - Absolute value graph

  1. #1
    Newbie
    Joined
    Mar 2009
    Posts
    14

    Absolute value graph

    ABS(2x + y) - ABS(x + 3y) = 8

    ABS = absolute value

    I need to know where to start
    Follow Math Help Forum on Facebook and Google+

  2. #2
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    \mid2x+y\mid-\midx+3y\mid=0

    This is what we wish to solve. \mid2x+y\mid-\midx+3y\mid=0

    We first must recognize that \mid2x+y\mid=2x+y or -(2x+y) . So, knowing this, can you finish up?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Mar 2009
    Posts
    14
    Quote Originally Posted by VonNemo19 View Post
    \mid2x+y\mid-\midx+3y\mid=0

    This is what we wish to solve. \mid2x+y\mid-\midx+3y\mid=0

    We first must recognize that \mid2x+y\mid=2x+y or -(2x+y) . So, knowing this, can you finish up?
    it says latex error in your first two lines, idk why
    Follow Math Help Forum on Facebook and Google+

  4. #4
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    When dealing with absolute value, you have to be aware of the folling fact-that \mid{x}\mid=\mid{-x}\mid=x So, therefore x can have 2 different values, but the corresponding value of y, or f(x) will have only one. So knowing that....

    We've got to set up different possibilities for the given expressions.

    \mid2x+y\mid=\pm(2x+y) and \mid{x+3y}\mid=\pm(x+3y).

    So, with this, can you take it from here?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    \sqrt{a^2+b^2}
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Newbie
    Joined
    Mar 2009
    Posts
    14
    i dont really know what you want me to do? what do i do after i get +- ?
    what does the square root formula have to do with this
    Follow Math Help Forum on Facebook and Google+

  7. #7
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    Solve for y for the different possibilities and then plot your graph.

    Pythagoras has nothing to do with this. I was showing my brother how to type in math code.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Newbie
    Joined
    Mar 2009
    Posts
    14
    Quote Originally Posted by VonNemo19 View Post
    Solve for y for the different possibilities and then plot your graph.

    Pythagoras has nothing to do with this. I was showing my brother how to type in math code.
    so we do
    2x + y = 8
    -2x - y = 8
    x + 3y = 8
    -x-3y = 8

    what do we do with the |2x + y| - |x + 3y| = 8
    what do we do with the - sign in the middle

    BTW this graph is on a coordinate plane, not on a number line
    Follow Math Help Forum on Facebook and Google+

  9. #9
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    It stays right were it is. you leave everything the same but the two expressions in the inequality signs
    Follow Math Help Forum on Facebook and Google+

  10. #10
    Newbie
    Joined
    Mar 2009
    Posts
    14
    Quote Originally Posted by VonNemo19 View Post
    It stays right were it is. you leave everything the same but the two expressions in the inequality signs
    ? i have no idea what youre talking about

    is it this
    2x + y - x - 3y = 8

    and you also do the other 3 possible equations and just set em equal to y and graph?

    Anyone can help? due tommorow
    Last edited by mathprob; May 4th 2009 at 06:02 PM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 8
    Last Post: May 23rd 2010, 10:59 PM
  2. Replies: 2
    Last Post: November 8th 2009, 01:52 PM
  3. Absolute Value Graph
    Posted in the Algebra Forum
    Replies: 5
    Last Post: June 16th 2009, 07:17 AM
  4. absolute value graph
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: February 10th 2009, 02:50 PM
  5. graph with absolute value
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: September 27th 2006, 10:59 PM

Search Tags


/mathhelpforum @mathhelpforum