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What is the equation of a circle with center (-1,-9) and radius 5?
A. (x - 1)2 + (y - 9)2 = 5
B. (x + 1)2 + (y + 9)2 = 5
C. (x + 1)2 + (y + 9)2 = 25
D. (x - 1)2 + (y - 9)2 = 25
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The formula for the equation of a circle is (x - c)² + (y - d)² = r² where (c, d) is the center and r is the radius. We know c, d, and r are -1, -9 and 5 respectively so the answer is (x + 1)² + (y + 9)² = 25.