Solve for x in the equation x squared plus 20 x plus 100 is equal to 36

The left side factors as a perfect square: x² + 20x + 100 = (x + 10)². Thus (x + 10)² = 36, so x + 10 = 6 or x + 10 = −6. Solving gives x = −4 or x = −16, which matches choice A.

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