Вправи до параграфів: §.13 (3)

3. Розв’яжіть систему нерівностей:

1. 16x2 ≥ 1, 3x < 9;

16x2 – 1 ≥ 0 x < 3

(4x – 1)(4x + 1) ≥ 0 x < 3

x ∈ (–∞; –14] ∪ [14; 3)

2. x2 < –15x x7 + 2 ≤ 0|x7

x2 + 15x < 0 x + 14 ≤ 0

x = 0 x = –15 x ≤ –14

B. x ∈ (–15; –14]

3. x2 + x – 20 ≤ 0; x2 > 9;

x1 = 4(x – 3)(x + 3) > 0 x = 3 x = –3

x2 = –5

x ∈ [–5; –3) ∪ (3; 4]

4. x2 – 5x – 24 > 0 |x| ≤ 7	x1 = 8	x2 = –3
x ∈ (–∞; –3) ∪ (8; + ∞)x ∈ [–7; 7]	x ∈ [–7; –3).