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