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Math Help - Writing the equation for parabolas

  1. #1
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    Writing the equation for parabolas

    I need to write the equation for a parabola that passes through the points (0,4),(-3,1) and has an axis of symmetry at x=-2
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  2. #2
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    Quote Originally Posted by Vuong View Post
    I need to write the equation for a parabola that passes through the points (0,4),(-3,1) and has an axis of symmetry at x=-2
    use the form ...

    y = a(x-h)^2 + k

    note that h = x-value of the vertex
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  3. #3
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    Quote Originally Posted by skeeter View Post
    use the form ...

    y = a(x-h)^2 + k

    note that h = x-value of the vertex
    What is a h and k?
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  4. #4
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    h is the horizontal translation and k is the vertical translation

    as the axis of symmetry is x = -2 then h = -2

    I.e y = a(x-(-2))^2 + k
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  5. #5
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    Quote Originally Posted by Vuong View Post
    What is a h and k?
    That's what you are to find- don't expect people to do the whole problem for you, you won't learn that way. skeeter did just tell you what h is: "h= x-value of vertex". You don't know what k (the y value of the vertex) is but you do h: "the parabola has an axis of symmetry at x= -2". Put in that value for h and you have an equation in a and k. Use the fact that (0,4) and (-3,1) are on the parabola, and so satisfy the equation, to get two equations to solve for a and k.
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