Question 805556
 Leave x in terms of y if...
t^2-4x^2t+4x^4=0
Factors to
(t-2x^2)(t-2x^2) = 0
t = 2x^2
:
and
{{{(t^2-1)/y}}} = {{{(t-1)/sqrt(y)}}}
cross multiply
{{{sqrt(y)}}}(t^2-1) = y(t-1)
{{{sqrt(y)}}}(t-1)(t+1) = y(t-1)
divide both sides by  (t-1)
{{{sqrt(y)}}}(t+1) = y
t + 1 = {{{y/sqrt(y)}}}
t + 1 = {{{sqrt(y)}}}
Replace t with 2x^2 from the 1st equation
2x^2 + 1 = {{{sqrt(y)}}}
square both sides
y = (2x^2+1)^2
FOIL
y = 4x^4 + 4x^2 + 1