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Math Help - Points on linear lines HELP!!!

  1. #1
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    Exclamation Points on linear lines HELP!!!

    I need help with two questions, and if you could explain how you came to the answer, i would be grateful.

    1. Which of the following points do not lie on the line:

    2y + 5x - 4 = 0

    a. ( -0.8 , 0 )
    b. ( -1 , 0.5 )
    c. ( 0 , 2 )
    d. ( 2 , 3)

    2. P is the point ( 3 , 5 ). Q is the point ( -1 , 9 ). R is the midpoint of PQ.

    Which of the following does R lie on?

    a. y = x + 6
    b. y = x + 8
    c. y = x - 6
    d. y = x - 8

    Thanks in advanced to anyone who can help.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by nugiboy View Post
    I need help with two questions, and if you could explain how you came to the answer, i would be grateful.

    1. Which of the following points do not lie on the line:

    2y + 5x - 4 = 0

    a. ( -0.8 , 0 )
    b. ( -1 , 0.5 )
    c. ( 0 , 2 )
    d. ( 2 , 3)
    first solve for y:

    y = - \frac 52x + 2

    now, plug in the x-coordinates of the points given and see if you get back the y-coordinates given, if you don't, then that point is not on the line.

    example, try (c): plug in x = 0, we get:

    y = - \frac 52(0) + 2 = 2

    since 2 was the y-coordinate given, this point is on the line. thus, this is not the point we are looking for


    2. P is the point ( 3 , 5 ). Q is the point ( -1 , 9 ). R is the midpoint of PQ.

    Which of the following does R lie on?

    a. y = x + 6
    b. y = x + 8
    c. y = x - 6
    d. y = x - 8

    Thanks in advanced to anyone who can help.
    use the midpoint formula to find R.

    recall: the midpoint between two points (x_1,y_1) and (x_2,y_2) is given by:

    \mbox {Midpoint } = \left( \frac {x_1 + x_2}2, \frac {y_1 + y_2}2 \right)

    once you have found R, do a similar procedure as in the previous problem
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