Chapter 0 - Section 0.6 - Solving Miscellaneous Equations - Exercises - Page 34: 4

$\pm \sqrt 3$

$x^{4}-x^{2}=6$ $x^{4}-x^{2}-6=0$ $x^{4}-3x^{2}+2x^{2}-6=0$ $(x^{4}-3x^{2})+(2x^{2}-6)=0$ $x^{2}(x^{2}-2)+2(x^{2}-3)=0$ $(x^{2}+2)(x^{2}-3)=0$ $x^{2}+2=0, undefined $ $imaginary $ $number$ $x^{2}-3=0, x=\pm\sqrt 3$