Interval notation???

Question

1: Write in interval notation: x < 2 OR x > 1

(- ∞ , 2)

(1, 2)

(-∞ , ∞ )

(1, ∞ )

2: Write in interval notation: x < 2 AND x ≥ 1

[1, ∞ )

(1, 2)

(-∞ , ∞ )

[1, 2)

3: Write in interval notation: x < 3 OR x < -1

(-1, 3)

(-∞ , 3)

(-∞ , -1)

(-∞ , ∞ )

4: Write in interval notation: x > 2 OR x ≤ 2

[2, ∞ )

(-∞ , ∞ )

(-∞ , 2)

(-2, 2]

5: Write in interval notation: x ≤ 5 AND x > 3

(3, 5]

(-∞ , 5]

(-∞ , 3)

(-∞ , ∞ )

Answer 1

Anytime you see a ≤ or a ≥ then the interval notation has either a [ or a ] because it includes the endpoint.  If the inequality is either &lt; or &gt; then the interval notation has either a ( or a ).  Positive and negative infinity always have parentheses ( or ) because you can never include infinity since it isn&#039;t a number.

1: Write in interval notation: x &lt; 2 OR x &gt; 1

(-∞ , ∞ )

2: Write in interval notation: x &lt; 2 AND x ≥ 1

[1, 2)

3: Write in interval notation: x &lt; 3 OR x &lt; -1

(-∞ , 3) because any x &lt; -1 is also less than 3.

4: Write in interval notation: x &gt; 2 OR x ≤ 2

(-∞ , ∞ )

5: Write in interval notation: x ≤ 5 AND x &gt; 3

(3, 5]

Hope this helps you!