Chapter 8 - Section 8.4 - Equations Quadratic in Form - Exercise Set - Page 635: 16

{$0,\pm \sqrt 5$}

Since, $u^2-u=6$ or, $u^2-u+6=0$ Factorize the expression as follows: $(u-3)(u+2)=0$ or, $u=${$-2,3$} Replace $u$ with $x^2-2$, we have $x^2-2=-2 \implies x=0$ and $x^2-2=3 \implies x^2=5$ or, $x=\pm \sqrt 5$ Hence, our solution set is $x=${$0,\pm \sqrt 5$}