$16 - (6 - 11x)^2 = 0$
$(4 - (6 - 11x))(4 + (6 - 11x)) = 0$
$4 - 6 + 11x_1 = 0$
$11x_1 = 2$
$x_1 = \frac{2}{11}$;
$4 + 6 - 11x_2 = 0$
$-11x_2 = -10$
$x_2 = -\frac{10}{11}$.

$(7m - 13)^2 - (9m + 19)^2 = 0$
$((7m - 13) - (9m + 19))((7m - 13) + (9m + 19)) = 0$
$7m_1 - 13 - 9m_1 - 19 = 0$
$-2m_1 = 32$
$m_1 = 32 : (-2)$
$m_1 = 16$;
$7m_2 - 13 + 9m_2 + 19 = 0$
$16m_2 = -6$
$m_2 = -\frac{6}{16} = -\frac{3}{8}$.