MathProblemSolver101

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UsernameMathProblemSolver101
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 #2
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$x^2+2y-9=-y^2+18x+9$

$x^2 -18x + y^2 +2y - 18 = 0$

$(x-9)^2 - 81 + (y+1)^2 - 1 - 18 = 0$

$(x-9)^2 + (y+1)^2 - 100 = 0$

$(x-9)^2 + (y+1)^2 = 100$

$(x-9)^2 + (y+1)^2 = 10^2$

$(x, y, r) = (9, -1, 10)$

$9 + (-1) + 10 = \boxed{18}$

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