Question
Question: If x<sup>2</sup> + 6x – 27 \> 0 and x<sup>2</sup> – 3x – 4 \< 0, then –...
If x2 + 6x – 27 > 0 and x2 – 3x – 4 < 0, then –
A
x > 3
B
x < 4
C
3 < x < 4
D
x = 3.5
Answer
3 < x < 4
Explanation
Solution
(x + 9) (x – 3) > 0; x2 – 3x – 4 < 0
x ∈ (–∞, –9) ∪ (3, ∞) (x – 4) (x + 1) < 0
⇒ x ∈ (–1, 4)
Hence, x ∈ (–1, 9) ∪ (3,4)