Question

помогите решить пример

Answer 1

Ответ:

-2,6

Объяснение:

3x² - 13x - 5 = 0

D = b² - 4*a*c. D = 169 + 60 = 229

x₁ = (-b - √D) / 2a = (13 - √229) / 6

x₂ = (-b + √D) / 2a = (13 + √229) / 6

$\dfrac{1}{x_{1}} + \dfrac{1}{x_{2}} = \dfrac{1}{\frac{13-\sqrt{229} }{6} } + \dfrac{1}{\frac{13+\sqrt{229}}{6} }= \dfrac{6}{13-\sqrt{229} } +\dfrac{6}{13+\sqrt{229} }=\dfrac{13 + \sqrt{229}}{-10}+\dfrac{13-\sqrt{229}}{-10}= -\dfrac{13+\sqrt{229}+13-\sqrt{229}}{10}= -\dfrac{13}{5}=-2,6$