Question

The solution to an inequality is given in set-builder notation as {x l x > two-thirds}. What is another way to represent this solution set?

(–∞ , two-thirds]
(–∞ , two-thirds)
(two-thirds, ∞)
[two-thirds, ∞)

Answer 1

The correct representation is (two-thirds, ∞), i.e. (2/3, ∞).

Reason: x > 2/3 excludes 2/3 so use a parenthesis at 2/3, and infinity is always with a parenthesis.