The solution set for 9 - (x + 4) < 0 is x > 5, and for 9 - (x + 4) ≥ 0, it is x ≥ 5. Both solutions are represented in interval notation as (5, ∞).
To solve the inequality 9 - (x + 4) < 0, follow these steps:
1. Simplify the expression inside the parentheses: 9 - x - 4 < 0.
2. Combine like terms: 5 - x < 0.
3. Subtract 5 from both sides: -x < -5.
4. Multiply both sides by -1 (since multiplying or dividing by a negative number flips the inequality sign): x > 5.
So, the solution set for the inequality 9 - (x + 4) < 0 is x > 5.
For part (b), the inequality is 9 - (x + 4) ≥ 0. Using the solution from part (a), since x > 5, the solution for part (b) is x ≥ 5.
Therefore, the solution set for (a) is x > 5, and for (b) is x ≥ 5, both expressed in interval notation as (5, ∞).