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Homework Help: Equation is a parabola with a vertical axis of symmetry

  1. Feb 24, 2005 #1
    Determine the restrictions on the constants A, C and E such that the following equation is a parabola with a vertical axis of symmetry.
    Ax^2+Cy^2+x+Ey=0

    a) A=0, C cannot=0, E cannot=0
    b) A=0, C cannot=0, E=0
    c) A cannot=0, C=0, E=0
    d) A cannot=0, C=0, E cannot=0

    i know that A cannot=0 and C=0....how about the x and y...what do they have to do with axis of symmetry?
     
  2. jcsd
  3. Feb 24, 2005 #2

    Galileo

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    Here's how you should not do it (I think):
    If C is zero you can immediately see you have the equation of a parabola with a vertical axis of symmetry. (This eliminates two answers)
    Suppose c) is the answer. It's obvious you don't have a parabola.
    So one answer remains.

    BTW: A parab. with a vertical axis of symmetry has the form y=a(x-b)^2+c
     
    Last edited: Feb 24, 2005
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