Question

Решить
Дано: x²+64/x²=65
Найти : x-8/x

Answer 1

$x^2 + \dfrac{64}{x^2} = 65\\\\x^2 + \dfrac{64}{x^2} - 16 = 65 - 16\\\\\left(x - \dfrac{8}{x}\right)^2 = 49\\\\x - \dfrac{8}{x} = \pm\sqrt{49} = \pm7$