Question

17. Sa se calculeze $\frac{1}{x1}+ \frac{1}{x2}$, stiind ca x1 si x2 sunt solutiile ecuatiei x²-x-2=0.

Answer 1

$\frac{1}{x_1} + \frac{1}{x_2} = \frac{x_1+x_2}{x_1\cdot x_2}= \frac{S}{P} = \frac{1}{-2} =- \frac{1}{2}$,
unde S=-b/a=1 si P=c/a=-2.