$3a + 0,6 = 9a^2 + 0,36$
$9a^2 + 0,36 - 3a - 0,6 = 0$
$9a^2 - 3a - 0,24 = 0$ |:3
$3a^2 - a - 0,08 = 0$
$D = 1^2 - 4 * 3 * (-0,08) = 1 + 0,96 = 1,96$
$a = \frac{1 ± \sqrt{1,96}}{6}$
$a_1 = \frac{1 - 1,4}{6} = \frac{-0,4}{6} = -\frac{4}{60} = -\frac{1}{15}$
$a_2 = \frac{1 + 1,4}{6} = \frac{2,4}{6} = \frac{24}{60} = \frac{2}{5}$
Ответ:
$a_1 = -\frac{1}{15}$;
$a_2 = \frac{2}{5}$.

$0,4a + 1,2 = 0,16a^2 + 1,44$
$0,16a^2 - 0,4a + 0,24 = 0$ |*100
$16a^2 - 40a + 24 = 0$ |:8
$2a^2 - 5a + 3 = 0$
$D = 5^2 - 4 * 2 * 3 = 25 - 24 = 1$
$a = \frac{5 ± \sqrt{1}}{4}$
$a_1 = \frac{5 - 1}{4} = \frac{4}{4} = 1$
$a_2 = \frac{5 + 1}{4} = \frac{6}{4} = 1,5$
Ответ:
$a_1 = 1$;
$a_2 = 1,5$.