Chapter 1 - Equations and Inequalities - 1.6 Other Types of Equations and Applications - 1.6 Exercises - Page 148: 87

$\{\pm 1,\pm \frac{\sqrt {10}}{2}\}$

Step 1. Let $u=x^2$, we have $2u^2-7u+5=0$ Step 2. Factor and solve: $(u-1)(2u-5)=0$ thus $u=1, \frac{5}{2}$ Step 3. For $u=1$, we have $x^2=1$ and $x=\pm 1$ Step 4. For $u=\frac{5}{2}$, we have $x^2=\frac{5}{2}$ and $x=\pm \frac{\sqrt {10}}{2}$ Step 5. Solution set $\{\pm 1,\pm \frac{\sqrt {10}}{2}\}$