$25 = 26x - x^2$
$26x - x^2 - 25 = 0$
$D = 13^2 - 1 * 25 = 169 - 25 = 144$
$x = 13 ± \sqrt{144}$
$x_1 = 13 - 12 = 1$
$x_2 = 13 + 12 = 25$
Ответ:
$x_1 = 1$;
$x_2 = 25$.

$3x^2 = 10 - 29x$
$3x^2 + 29x - 10 = 0$
$D = 29^2 - 4 * 3 * (-10) = 841 + 120 = 961$
$x = \frac{-29 ± \sqrt{961}}{6}$
$x_1 = \frac{-29 - 31}{6} = \frac{-60}{6} = -10$
$x_2 = \frac{-29 + 31}{6} = \frac{2}{6} = \frac{1}{3}$
Ответ:
$x_1 = -10$;
$x_2 = \frac{1}{3}$.

$y^2 = 4y + 96$
$y^2 - 4y - 96 = 0$
$D = 2^2 - 1 * (-96) = 4 + 96 = 100$
$y = 2 ± \sqrt{100}$
$y_1 = 2 - 10 = -8$
$y_2 = 2 + 10 = 12$
Ответ:
$y_1 = -8$;
$y_2 = 12$.

$3p^2 + 3 = 10p$
$3p^2 - 10p + 3 = 0$
$D = 5^2 - 3 * 3 = 25 - 9 = 16$
$p = \frac{5 ± \sqrt{16}}{3}$
$p_1 = \frac{5 - 4}{3} = \frac{1}{3}$
$p_2 = \frac{5 + 4}{3} = \frac{9}{3} = 3$
Ответ:
$p_1 = \frac{1}{3}$;
$p_2 = 3$.

$x^2 - 20x = 20x + 100$
$x^2 - 20x - 20x - 100 = 0$
$x^2 - 40x - 100 = 0$
$D = 20^2 - 1 * (-100) = 500$
$x = 20 ± \sqrt{500} = 20 ± 10\sqrt{50}$

$25x^2 - 13x = 10x^2 - 7$
$25x^2 - 13x - 10x^2 + 7 = 0$
$D = 13^2 - 4 * 15 * 7 = 169 - 420 = 251 < 0$
Уравнение не имеет корней.