Now, write x² - 16x + 64 = -8 as (x - 8)² = -16(x - 8)² = -8(x - 16)² = -16(x - 16)² = -8

The left side is a perfect-square trinomial: x² − 16x + 64 = (x − 8)², since half of −16 is −8 and (−8)² = 64. Keeping the right side unchanged gives (x − 8)² = −8, which is choice B.

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