One interval is given in interval notation, another in set-builder notation. Match the equivalent intervals.
1. (-∞, ∞)
2. (-∞, 4)
3. [4, ∞)
4. (4, ∞)
a. {x l 4 ≤ x < ∞}
b. {x l 4 < x < ∞}
c. {x l - ∞ < x < 4}
d. {x l x ∈ ℝ}
1. (-∞, ∞) - d. {x l x ∈ ℝ}
2. (-∞, 4) - c. {x l - ∞ < x < 4}
3. [4, ∞) - a. {x l 4 ≤ x < ∞}
4. (4, ∞) - b. {x l 4 < x < ∞}