Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

The domain of $f(x)=\log_{\tan x}(2\sin x-1)$ is

Options:

$\underset{n∈I}{U}\left(2nπ+\frac{π}{6},\,2nπ+\frac{π}{4}\right)∪\left(2nπ+\frac{π}{6},\,(4n+1)\frac{π}{2}\right)$

$\underset{n∈I}{U}\left(2nπ+\frac{π}{6},\,2nπ+\frac{5π}{6}\right)$

$\underset{n∈I}{U}\left(2nπ,(2n+1)\right)$

none of these

Correct Answer:

$\underset{n∈I}{U}\left(2nπ+\frac{π}{6},\,2nπ+\frac{π}{4}\right)∪\left(2nπ+\frac{π}{6},\,(4n+1)\frac{π}{2}\right)$

Explanation:

$log_{\tan x} (2\sin x-1)$ is defined only when

$2\sin x −1> 0$ and $\tan x > 0$ and $\tan x ≠1$

$⇒x∈\left(2nπ+\frac{π}{6},\,2nπ+\frac{π}{4}\right)∪\left(2nπ+\frac{π}{6},\,(4n+1)\frac{π}{2}\right)$