1) 5x^2-18x+16

2) 3x^2-11x-14

3) x^2-x-1

решить через дискриминант

1) 5x² - 18x + 16 = 0

D = b² - 4ac = 324 - 4 * 5 * 16 = 324 - 320 = 4 = 2²

x1 = (18 + 2) / 10 = 2

x2 = (18 - 2) / 10 = 1,6

2) 3x² - 11x - 14 = 0

D = b² - 4ac = 121 - 4*3 * (-14) = 121 + 168 = 289 = 17²

x1 = (11 + 17) / 6 = 28/6 = 4 4/6 = 4 2/3

x2 = (11 - 17) / 6 = - 1

3) x² - x - 1 = 0

D = b² - 4ac = 1 - 4 * (- 1) = 1 + 4 = 5

x1 = (1 + √5) / 2

x2 = (1 - √5) / 2