a² - b² = (a + b)(a - b)
(a +- b)² = a² +- 2ab + b²
((√2 + √8)² - 6)((√2 - √8)² + 6) = (2 + 2√16 + 8 - 6)(2 - 2√16 + 8 + 6) = 12*8 = 96
x² + 1/x² = 7
x + 1/x = 3
(x + 1/x)² = 3²
1/x² +2*x*1/x + x² = 9
x² + 2 + 1/x² = 9
