Question

Решить неравенство:
$x ^{2} - 10x + 21 > 0$

Answer 1

$x ^{2} - 10x + 21 > 0 \\ x ^{2} - 10x + 21 = 0 \\ x_{1} + x_{2} = 10 \\ x_{1} \times x_{2} =21 \\ x_{1} = 3 \\ x_{2} =7 \\ \\ ( - \infty ;3) U(7 ; + \infty )$