SOLUTION: x^2+y^2+8x-6y=0 find the center and radius

Question 599205: x^2+y^2+8x-6y=0
find the center and radius
Answer by math-vortex(648) (Show Source): You can put this solution on YOUR website!
Hi, there--
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The equation for a circle has the form

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The ordered pair (h,k) is the center of the circle and r is the radius. We need to transform the given equation to this form to find the center and radius.
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We will use the "completing the square" method. The polynomial x^2+8x+16 is a perfect square [(8/2)^2=16], so we need to add 16 to both sides of the equation and re-arrange the terms.
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The polynomial y^2-6y+9 is a perfect square, so we need to add 9 to both sides of the equation.

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Now write the polynomial expressions in factored form.

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Then write the constant term as the square of a number.

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The equation is now in standard form, so the center=(h,k) is (-4,3), and the radius is 5.
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That's it. Feel free to email via my gmail account if you have questions about the solution.
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Ms.Figgy
math.in.the.vortex@gmail.com
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