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Math Help - circle

  1. #1
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    circle

    Show that the equation


    5y2+3x2+19=4x−2x2−20y


    represents a circle by rearranging it into the centre-radius form of the equation of a circle. State the coordinates of the center and the radius of the circle.


    what is the center and what is the radius??
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  2. #2
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    sorry the equation should be

    5y^2+3x^2+19=4x-2x^2-20y
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  3. #3
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    Quote Originally Posted by pourcarlos View Post
    Show that the equation


    5y2+3x2+19=4x−2x2−20y


    represents a circle by rearranging it into the centre-radius form of the equation of a circle. State the coordinates of the center and the radius of the circle.


    what is the center and what is the radius??
    5y^2+3x^2+19 = 4x-2x^2-20y

    5x^2-4x+5y^2+20y = -19

    x^2 - \frac{4}{5}x + y^2 + 4y = -\frac{19}{5}

    x^2 - \frac{4}{5}x + \frac{4}{25} + y^2 + 4y + 4 = -\frac{19}{5} + \frac{4}{25} + 4

    \left(x - \frac{2}{5}\right)^2 + (y + 2)^2 = \left(\frac{3}{5}\right)^2

    the last equation is in standard form for a circle ... look that up in your text to determine the center and radius.
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  4. #4
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    ohhh i see, thank you!
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