Question
Question: If (cot<sup>–1</sup> x)<sup>2</sup> – 3 (cot<sup>–1</sup> x) + 2 \> 0, then x lies in...
If (cot–1 x)2 – 3 (cot–1 x) + 2 > 0, then x lies in
A
(cot 2, cot 1)
B
(– ¥, cot 2) È (cot 1, ¥)
C
(cot 1, ¥)
D
(–¥, cot 1) È (cot 2, ¥)
Answer
(– ¥, cot 2) È (cot 1, ¥)
Explanation
Solution
(cot–1 x – 1) (cot–1 x – 2) > 0 ̃ x < cot 2 or x > cot 1
(cot–1 x is a decreasing function)