What are the center and radius of the circle x^2 + y^2 + 2x + 6y - 26 = 0?
Answer and explanation
Correct answer: D. center (-1, -3), radius 6
- Step 1: Complete the square in x and in y.
- Step 2: (x - -1)^2 + (y - -3)^2 = 36, so the center is (-1, -3) and the radius is 6.
Answer
center (-1, -3), radius 6.
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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