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Math Help - work out the co ordinates

  1. #1
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    work out the co ordinates

    hi,

    i need to work out the co ordinates of two points that the graph of y=2x-1 passes through.

    i don't really know how to do this so could somone explain what i have to do please?!?

    thanks!
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  2. #2
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    e^(i*pi)'s Avatar
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    Pick any old values of x and put the corresponding y value in.

    For example (0,-1) is a point on the line
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  3. #3
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    oh so would (1, -1) be one aswell?
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  4. #4
    Super Member TheChaz's Avatar
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    Quote Originally Posted by andyboy179 View Post
    oh so would (1, -1) be one aswell?
    No. (x, y) = (1, -1) is NOT on the line since using these values in
    y = 2x - 1 gives us
    -1 = 2(1) -1, which is FALSE.
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  5. #5
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    e^(i*pi)'s Avatar
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    No, what makes you say that?

    The equation is a straight line. If you want to use x=1 then it would be (1, [2 \cdot 1 - 1])
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  6. #6
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    would (-1,0) work?
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  7. #7
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by andyboy179 View Post
    would (-1,0) work?
    Sub it into the equation and check. Does (2 \times -1) -1 equal 0?
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  8. #8
    Super Member TheChaz's Avatar
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    When x = -1,
    y = 2x - 1 becomes
    y = 2(-1) - 1 =
    -2 -1 = -3
    S0 (-1, -3) is the point
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  9. #9
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    oh i see now, thanks alot!
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  10. #10
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    no its -1
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  11. #11
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    Uhm, you don't simply search numbers that verify the equation, but take the intersection with the axes (make x=0 and find y, then make y=0 and find x).
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  12. #12
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    That's only necessary to find the x- and y-intercepts. For any two points on the line, any two values of x suffice.
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  13. #13
    Grand Panjandrum
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    Quote Originally Posted by andyboy179 View Post
    oh so would (1, -1) be one aswell?
    Quote what you are responding to otherwise the thread will become confusing.

    CB
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  14. #14
    Grand Panjandrum
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    Quote Originally Posted by e^(i*pi) View Post
    No, what makes you say that?

    The equation is a straight line. If you want to use x=1 then it would be (1, [2 \cdot 1 - 1])
    Quote what you are responding to, otherwise the thread will become incomprehensible.

    CB
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  15. #15
    Grand Panjandrum
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    Quote Originally Posted by andyboy179 View Post
    would (-1,0) work?
    Quote, or don't bother replying thank you.

    CB
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