-4x v kvodrate+13x+12bol'we0?

- 4 x^2 + 13 x + 12 > 0

- 4 x^2 + 13 x + 12 = 0
4 x^2 - 13x - 12 = 0
D = (-13)^2 - 4 * 4 * (-12) = 169 + 192 = 361 = 19^2

x = (13 +/- 19) / 8
x1 = 4
x2 = -0.75

- (4x + 3)(x - 4) > 0
(4x + 3)(x - 4) < 0

методом интервалов

_____ - 0,75 _______ +4 _________
>=0 _________ <0 _______>= 0____

Ответ: (-0,75; 4)