6
QuizMultiple Choice

Equation of a Circle (Sec 9-3)

Question 6 • Math II CR S2 RS3

Mrs. Culland is finding the center of a circle whose equation is x2 + y2 + 6x + 4y – 3 = 0 by completing the square. Her work is shown.x2 + y2 + 6x + 4y – 3 = 0x2 + 6x + y2 + 4y – 3 = 0(x2 + 6x) + (y2 + 4y) = 3(x2 + 6x + 9) + (y2 + 4y + 4) = 3 + 9 + 4

Answer
A
(x – 3)2 + (y – 2)2 = 42, so the center is (3, 2).
B
(x + 3)2 + (y + 2)2 = 42, so the center is (3, 2).
C
(x – 3)2 + (y – 2)2 = 42, so the center is (–3, –2).
D
(x + 3)2 + (y + 2)2 = 42, so the center is (–3, –2).
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