Ответ: х1 = 1+√2 ; х2 = 1-√2
А) (х + 2)(х - 5) - 3x(1 - 2x) = х² - 5х + 2х - 10 - 3х + 6х² = 7х² - 6х - 10
б) Если х = -1, то 7х² - 6х - 10 = 7 × (-1)² - 6 × (-1) - 10 = 7 × 1 + 6 - 10 = 7 + 6 - 10 = 13 - 10 = 3
(14-2 11/12:7/18):4 7/8= 1 1/3
1) 2 11/12 : 7/18 = 35/12 * 18/7 = 5/2 * 3/1 = 15/2
2) 14 - 15/2 = 28/2 - 15/2 = 13/2
3) 13/2 : 4 7/8 = 13/2 : 39/8 = 13/2 * 8/39 = 1/1 * 4/3 = 4/3 = 1 1/3