Question

решите уравнения
a) x^2-x-1=0;
б) x/5 + 1/x =4

Answer 1

${x}^{2} - x - 1 = 0 \\ d \: = { (- 1)}^{2} - 4 \times 1 \times ( - 1) = 5 \\ x = \frac{ 1 \frac{ + }{} \sqrt{5} }{2}$
2.
$\frac{x}{5} + \frac{1}{x} = 4 \\ х \: \: не \: \: равен \: 0 \\ \frac {{x}^{2} }{5} + 1 = 4x \\ {x}^{2} -20x + 5 = 0 \\ d = 400 - 20 = 380 \\ x = \frac{20 \frac{ + }{} 2\sqrt{95} }{2} = 10 \frac{ + }{ } \sqrt{95}$