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Math Help - one last quadratics question!

  1. #1
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    one last quadratics question!

    sorry, last one i swear!
    please help, thankyou all!

    Find the points of intersection between the porabola and line:

    y = x^2 + 12x + 24
    y = 4x + 9


    !!
    i thought i had more brain cells than that!
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  2. #2
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    Hello, georgiaaa!

    Find the points of intersection of the parabola and line:
    . . y .= .x + 12x + 24
    . . y .= .4x + 9

    To find the intersection of two curves, equate the functions.

    . . x + 12x + 24 .= .4x + 9

    . . . x + 8x + 15 .= .0

    . . (x + 3)(x + 5) .= .0

    And we have: .x = -3, -5

    The corresponding values are: .y = -3, -11


    Therefore, the intersections are: .(-3,-3) and (-5,-11)

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  3. #3
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by georgiaaa. View Post
    sorry, last one i swear!
    please help, thankyou all!

    Find the points of intersection between the porabola and line:

    y = x^2 + 12x + 24
    y = 4x + 9


    !!
    i thought i had more brain cells than that!
    the parabola and the line will intersect where:

    x^2 + 12x + 24 = 4x + 9
    => x^2 + 8x + 15 = 0
    => (x + 5)(x + 3) = 0
    => x = -5 or x = -3

    when x = -5
    y = 4(-5) + 9 = -11

    when x = -3
    y = 4(-3) + 9 = -3

    so they intersect at (-5,-11) and (-3,-3)

    EDIT: Beaten again!
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