Відповіді на вправи: 470

1) x² + 4x + 3 $\le$ 0;

x² + 4x + 3 = 0;

x₁ = –6, x₂ = 2;

x $\in$ [–3; –1].

2) x² – 3х – 28 < 0;

x² – 3х – 28 = 0;

x₁ = –4, x₂ = 7;

x $\in$ (–4; 7).

3) x² + 6x + 9 > 0;

x² + 6x + 9 = 0;

(x + 3)² = 0;

x + 3 = 0;

x = –3.

4) x² + x – 12 < 0;

x² + x – 12 = 0;

x₁ = –4, x₂ = 3;

x $\in$ (–4; 3)

x $\in$ (–$\infty$; –3) $\cup$ (–3; +$\infty$).

5) x² – 5x – 6 $\ge$ 0;

x² – 5x – 6 = 0;

x₁ = –1, x₂ = 6;

x $\in$ (–$\infty$; –1] $\cup$ [6; +$\infty$).

6) –x² + 7x – 12 > 0 | • (–1);

x² – 7x + 12 < 0;

x₁ = 3, x₂ = 4;

x $\in$ (3; 4).

7) –x² + 5x + 14 > 0 |• (–1);

x² – 5x – 4 < 0;

x² – 5x – 14 = 0;

x₁ = –2, x₂ = 7;

x $\in$ (–2; 7).

8) x² + 7x – 8 $\le$ 0;

x² + 7x – 8 = 0;

x₁ = –8, x₂ = 1;

x $\in$ [–8; 1].