Question

Теңсіздіктерді шеші
5. 1) х2 -х – 56 > 0;
2) х2 + х - 90 < 0;
3)-х2+х-210<0;​

Answer 1

$1) {x}^{2} - x - 56 0 \\ x1 \times x2 = - 56 \\ x1 + x2 = 1 \\ x1 = 8 \\ x2 = - 7 \\ (x - 8)(x + 7) 0$

х€(- бесконечность;-7) и (8;+бесконечность)

$2) {x}^{2} + x - 90 < 0 \\ x1 \times x2 = - 90 \\ x1 + x2 = - 1\\x1 = 9 \\ x2 = - 10 \\ (x - 9)(x + 10) < 0$

х€(-10;9)

$3) - {x}^{2} + x - 210 < 0 \\ dis = 1 - 4 \times ( - 210) \times ( - 1) = 1 - 840 = - 839 < 0$

нет корней

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