(x + 2) (x - 2) - (x - 1)² = 16

=> x² - 2x + 2x - 4 - (x - 1)² = 16

=> x² - 4 - (x² - 2x + 1) = 16

=> x² - 4 - x² + 2x - 1 = 16

=> -5 + 2x = 16

=> 2x = 21

=> x = 10,5

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