Chapter 5 - Polynomials and Factoring - 5.7 Solving Quadratic Equations by Factoring - 5.7 Exercise Set - Page 353: 82

$$a=\frac{7}{10},\:a=-\frac{7}{10}$$

In order to solve the equation, we first simplify both sides of the equation. Next, we isolate the variable. Doing this, we find: $$ a^2=\frac{49}{100} \\ a=\sqrt{\frac{49}{100}},\:a=-\sqrt{\frac{49}{100}} \\ a=\frac{7}{10},\:a=-\frac{7}{10}$$