6. 3x² - 7x - 6 ≤ 0
D = 49 + 72 = 121
x1 = (7-11)/6 = -2/3
x2 = (7+11)/6 = 3
__+___[-2/3]____-____[3]____+___
Ответ: [-2/3; 3]
7.
2x² + x - 3 > 0
D = 1 + 24 = 25
x1 = (-1-5)/4 = -3/2
x2 = (-1+5)/4 = 1
___+__(-1,5)_____-____(1)___+____
Ответ: (-∞; -1,5) U (1; +∞)
8.
__+___(-3)_-__[-2]__-___(0)____+__[2]____-___
Ответ: (-∞; -3) U {-2} U (0; 2]