Question

x^2-x-20=0 помогите срочно!​

Answer 1

Ответ:

$x_1 = 5 \\ x_2 = - 4$

Объяснение:

${x}^{2} - x - 20 = 0 \\ D = {( - 1)}^{2} - 4 \times 1 \times ( - 20) = 1+ 80 = 81 \\ \sqrt{D} = \sqrt{81} = 9 \\ x_1 = \frac{1 + 9}{2} = \frac{10}{2} = 5 \\ x_2 = \frac{1 - 9}{2} = \frac{ - 8}{2} = - 4$