Solve x2 – 8x = 20 by completing the square. Which is the solution set of the equation?

To complete the square, add half of −8 squared, which is 16, to both sides: x² − 8x + 16 = 20 + 16. This gives (x − 4)² = 36, so x − 4 = ±6 and x = 10 or x = −2. The solution set is {−2, 10}, choice D.

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