Question

рощвяжіть будь ласка,даю 100 балів​

Answer 1

По теореме Виета:

${x}^{2} + bx + c = 0\\ x_{1} + x_{2} = - b\\ x_{1} x_{2} = c$

${x}^{2} + 10x - 4 = 0 \\ x_{1} + x_{2} = - 10 \\ x_{1} x_{2} = - 4\\ \frac{1}{x_{1}} + \frac{1}{x_{2}} = \frac{x_{1} + x_{2}}{x_{1}x_{2}} = \frac{ - 10}{ - 4} = \frac{5}{2} = 2.5$