X^2 - 5x + 6 = 0
D = b^2 - 4ac
D = -5^2 - 4 * 1 * 6 = 25 - 24
D = 1
x1 = 5 + 1 / 2 = 3
x2 = 5 - 1 / 2 = 2
Ответ : x1 = 3 ; x2 = 2
5x^2 - 9x - 2 = 0
D = b^2 - 4ac
D = -9^2 - 4 * 5 * (-2) = 81 + 40 = 121
D = 11
x1 = 9 + 11 /2 = 9
x2 = 9 - 11 / 2 = -1
Ответ : x1 = 9 ; x2 = -1