Match the equation 4x^6-2x^3+1=0. With a substitution from the column that could be used to reduced the equation to quadratic form:
a) u=x^-1/3
b) u=x^1/3
c) u=x^-2
d) u=x^2
e) u=x^-2/3
f) u=x^3
g) u=x^2/3
h) u= x^4
strange wording.
clearly let u = x^3, then
we get
4u^2 - 2u + 1 = 0
u = (2 ± √-12)/8
I don't know if you had to go this far, but clearly u is a complex number.
you would then have to take the cube root of a complex number.