Question 248303
Find the coordinates of the center and the radius of each circle whose equation is given. Then draw the graph.

#31)

{{{x^2+y^2+6y=-50-14x}}}

I am confused about what to do after expanding the y^2+6y part to (y+6y+9)^2.  The "-14x" is also confusing me.
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Rewrite:
x^2 + 14x + ? + y^2 + 6y + ? = -50 + ?
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Complete the square on the x-terms and on the y-terms:
x^2 + 14x + 49 + y^2 + 6y + 9 = -50 + 49 + 9
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(x+7)^2 + (y+3)^2 = 8
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Center at (-7,-3)
Radius = sqrt(8) = 2sqrt(2)
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Cheers,
Stan H.