Chapter 1 - Equations and Inequalities - 1.6 Other Types of Equations and Applications - 1.6 Exercises - Page 148: 103

$\{\pm\frac{1}{2},\pm4\}$

Step 1. Let $u=(x)^{-2}$, we have $16u^2-65u+4=0$ Step 2. Factor and solve: $(u-4)(16u-1)=0$ thus $u=\frac{1}{16}, 4$ Step 3. For $u=\frac{1}{16}$, we have $(x)^{-2}=\frac{1}{16}$ thus $x=\pm4$ Step 4. For $u=4$, we have $(x)^{-2}=4$ thus $x=\pm\frac{1}{2}$ Step 5. Solution set $\{\pm\frac{1}{2},\pm4\}$