Question

ребята кто знает ответ можете пожалуйста помочь мне

Answer 1

Ответ:

$1) {x}^{2} - 10x - 11 = 0 \\ x1x2 = - 11 \\ x1 + x2 = 10 \\ \\ x1 = 11 \\ x2 = - 1$

$2) {x}^{2} + 13x + 12 = 0 \\ x1x2 = 12 \\ x1 + x2 = - 13 \\ \\ x1 = - 12 \\ x2 = - 1$

$3)2 {x}^{2} + 5x - 7 = 0 \\ d = 25 - 4 \times 2 \times ( - 7) = 25 + 56 = 81 \\ \sqrt{d} = 9 \\ x1 = \frac{ - 5 - 9}{4} = - \frac{14}{4} = - 3.5 \\ x2 = \frac{ - 5 + 9}{4} = \frac{4}{4} = 1$

$4)5 {x}^{2} - 4x - 9 = 0 \\ d = 16 - 4 \times 5 \times ( - 9) = 16 + 180 = 196 \\ \sqrt{d} = 14 \\ x1 = \frac{4 - 14}{10} = - 1 \\ x2 = \frac{4 + 14}{10} = 1.8$