Question

Решите уравнение
х²+9х+20=0

Answer 1

${x}^{2} + 9x + 20 = 0 \\ a = 1 \\ b = 9 \\ c = 20 \\ d = {b}^{2} - 4ac = {9}^{2} - 4 \times 1 \times 20 = 1 \\ x1 = \frac{ - b + \sqrt{d} }{2a} = \frac{ - 9 + \sqrt{1} }{2 \times 1} = - 4 \\ x2 = \frac{ - b - \sqrt{d} }{2a} = \frac{ - 9 - 1}{2 \times 1} = - 5$

Ответ : х1 = -4; х2 = -5