Question

x²-9>0;
x²-10x+21≥0
будь ласка!​

Answer 1

${x}^{2} - 9 > 0 \\ (x - 3)(x + 3) > 0 \\ x - 3 > 0 \: \: \: \: \: x > 3 \\ x + 3 > 0 \: \: \: \: \: x > - 3$

${x}^{2} - 10x + 21 \geqslant 0$

$x1 + x2 = 10 \\ x1 \times x2 = 21 \\ x1 \geqslant 3 \\ x2 \geqslant 7$