2X^4-x^2-6>0

2X^4-x^2-6>0

Let X & sup2; = t ≥ x ^ 4 = T & sup2;
2t²-t-6>0
(2t+3)(t-2)>0
The solution is T2
Because t > 0, t > 2
That is X & sup2; > 2
So x √ 2