What is the center of a circle whose equation is x2 + y2 + 4x – 8y + 11 = 0?

Group the x-terms and y-terms, then complete the square: x² + 4x + y² − 8y + 11 = 0 becomes (x + 2)² + (y − 4)² = 9. A circle in this form, (x − h)² + (y − k)² = r², has center (h, k). Therefore the center is (−2, 4), choice A.

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