Please explain the steps on to solve this equation.

Question

x^-6 - 8x^-3 + 16 = 0

k^-4/3 - 10k^-2/3 + 21 = 0

Answer 1

x^-6 - 8x^-3 + 16 = 0

Put x^(-3) = y. Then:

y^2 - 8 y + 16 = 0 --->

(y - 4)^2 = 0 --->

y = 4 ---->

x = 4^(-1/3) = 2^(-2/3)