Solve x2 + 12x = –11 by completing the square. Which is the solution set of the equation?

To complete the square, add 36 to both sides, since half of 12 is 6 and 6² = 36. Then (x + 6)² = 25, so x + 6 = 5 or x + 6 = −5. Thus x = −1 or x = −11, making {−11, −1} the solution set.

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