What are the center and radius of the circle x^2 + y^2 - 2x - 4y - 4 = 0?
Answer and explanation
Correct answer: C. center (1, 2), radius 3
- Step 1: Complete the square in x and in y.
- Step 2: (x - 1)^2 + (y - 2)^2 = 9, so the center is (1, 2) and the radius is 3.
Answer
center (1, 2), radius 3.
Why not the others: The center has the opposite signs of the linear coefficients halved, and the right-hand side is the radius squared.
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