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Math Help - Functions and graphs question..

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    Functions and graphs question..

    A curve with equation y = ax^2 + bx + c crossed the x-axis at (-4,0) and (0,0) and also passes through the point (2,120). Where does the curve cross the y-axis?
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    Quote Originally Posted by struck View Post
    A curve with equation y = ax^2 + bx + c crossed the x-axis at (-4,0) and (0,0) and also passes through the point (2,120). Where does the curve cross the y-axis?
    The y-intercept occurs where x = 0.

    You're told that the curve passes through the origin.

    Therefore the y-intercept must be 0.
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    I knew that and I posted the question wrong .. It should have been (0,9) not (0,0) . It just didn't appear to me that the equation should be made of type a(x - s)(x - r) (or similar) .. I solved it though

    Thanks for the reply.
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    Quote Originally Posted by struck View Post
    A curve with equation y = ax^2 + bx + c crossed the x-axis at (-4,0) and (0,9) and also passes through the point (2,120). Where does the curve cross the y-axis?
    You have been given three points, being three sets of values for x and y. Plug these values into the given equation:

    . . . . . 0\, =\, 16a\, -\, 4b\, +\, c

    . . . . . 9\, =\, c

    . . . . . 120\, =\, 4a\, +\, 2b\, +\, c

    Solve the system of equations.
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