1. x + 9 = 0.

Давай решим уравнения по порядку: 1. $x + 9 = 0 \Rightarrow x = -9$ 2. $x - 7 = 0 \Rightarrow x = 7$ 3. $x + 5 = 12 \Rightarrow x = 12 - 5 \Rightarrow x = 7$ 4. $17 + x = 20 \Rightarrow x = 20 - 17 \Rightarrow x = 3$ 5. $3x + 7 = 4 \Rightarrow 3x = 4 - 7 \Rightarrow 3x = -3 \Rightarrow x = -1$ 6. $2x - 5 = 3 \Rightarrow 2x = 3 + 5 \Rightarrow 2x = 8 \Rightarrow x = 4$ 7. $3x - 1 = 8 \Rightarrow 3x = 8 + 1 \Rightarrow 3x = 9 \Rightarrow x = 3$ 8. $5 - 2x = 3 \Rightarrow -2x = 3 - 5 \Rightarrow -2x = -2 \Rightarrow x = 1$ 9. $7 + 4x = 5x \Rightarrow 7 = 5x - 4x \Rightarrow x = 7$ 10. $4(x + 1) - 3 = 5 \Rightarrow 4x + 4 - 3 = 5 \Rightarrow 4x + 1 = 5 \Rightarrow 4x = 4 \Rightarrow x = 1$ 11. $2(x + 5) - 3 = 9 \Rightarrow 2x + 10 - 3 = 9 \Rightarrow 2x + 7 = 9 \Rightarrow 2x = 2 \Rightarrow x = 1$ 12. $7 + 4(x + 1) = 15 \Rightarrow 7 + 4x + 4 = 15 \Rightarrow 4x + 11 = 15 \Rightarrow 4x = 4 \Rightarrow x = 1$ 13. $x + 2(x + 7) = 8 \Rightarrow x + 2x + 14 = 8 \Rightarrow 3x = 8 - 14 \Rightarrow 3x = -6 \Rightarrow x = -2$ 14. $2x + 2(x + 3) = 10 \Rightarrow 2x + 2x + 6 = 10 \Rightarrow 4x = 4 \Rightarrow x = 1$