Given the function [tex]y=x^4+6x^2-5[/tex].
The critical value occurs when y' = 0.
[tex]y'=0 \\ \\ \Rightarrow4x^3+12x=0 \\ \\ \Rightarrow x(4x^2+12)=0 \\ \\ \Rightarrow x=0 \ or \ 4(x^2+3)=0 \\ \\ 4(x^2+3)=0 \\ \\ \Rightarrow x^2+3=0 \\ \\ \Rightarrow x^2=-3 \\ \\ \Rightarrow x=\pm i \sqrt{3} \\ \\ \therefore \ the \ critical \ values \ are \ -i\sqrt{3}, \ 0, \ i\sqrt{3}[/tex]
Therefore, from the given answer options the answer is none.
