Question

x6 − 6x3 − 7 = 0

Answer 1

let x^3 = a

a^2 - 6a - 7 = 0
(a - 7)(a + 1) = 0
a = 7

a = -1

x^3 = 7
x^3 = -1

x = cuberoot of 7
x = -1