Question

PLEASE TRY TO ANSWER OK​

Answer 1

$x = 4 + \sqrt{15} \\ \frac{1}{x} = \frac{1}{4 + \sqrt{15} } \\ \frac{1}{x} = \frac{1}{4 + \sqrt{15} } \times \frac{4 - \sqrt{15} }{4 - \sqrt{15} } \\ = \frac{4 - \sqrt{15} }{16 - 15} \\ = 4 - \sqrt{15} \\ x + \frac{1}{x} = 4 + \sqrt{15} + 4 - \sqrt{15} \\ = 8 \\ ( {x + \frac{1}{x} })^{2} = 16 \\ {x}^{2} + \frac{1}{ {x}^{2} } + 2 = 8 \\ \implies {x}^{2} + \frac{1}{ {x}^{2} } = 6$