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Help with linear equations

  1. Sep 6, 2006 #1
    Could someone please explain how to graph y=x-2 and y=4-x
    and find the coordinates of the point of intersection.
     
  2. jcsd
  3. Sep 6, 2006 #2

    TD

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    If the coördinates are the same, then surely the y-values are.
    Let both expressions for y in terms of x equal and solve for x.
     
  4. Sep 6, 2006 #3

    HallsofIvy

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    y= x-2

    If x= 0, what is y?

    If x= 2, what is y?

    can you plot those two (x,y) points?

    Since the graph of y= x- 2 is a straight line just draw the line between those two points.

    Now do exactly the same thing using y= 4- x
    If x= 0, what is y?
    If x= 2, what is y?

    Plot those two (x,y) points and draw the line through them.

    Where do those two line cross?
     
  5. Sep 6, 2006 #4
    do I use y=mx+b?????

    How would I find out what y equals?
     
  6. Sep 7, 2006 #5

    TD

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    Where you able to find the two points HallsofIvy asked you to?
    He was guiding you to the interesection points of the axis, allowing you to graph the line.
    Then, you can graphically find the coördinates of the point of intersection.

    If you need to find it algebraically, did you understand my suggestion?
     
  7. Sep 7, 2006 #6

    HallsofIvy

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    You said you were given y=x-2 and y=4-x. Why not use them?

    How do you find out what y equals? Do the arithemetic! What do you think "y= x- 2" means?
     
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