True or false II

now since x>0, apply a.m-g.m: $x^4+x^{-4}≥2\sqrt{x^4*x^{-4}}=2$ so $x^4+x^{-4}+3≥2+3=\boxed{5}$ so this indeed is $\boxed{true}$ .

x^4 + 3 +x^(-4) >= 5 is equivalent to x^4 - 2 + x^(-4) >=0. Multiplying by x^4, x^8 -2x^4 + 1 >=0, or (x^4 - 1)^2 >= 0, so true. Seems that x could be < 0.