Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

Find the domain of function $f(x)=\log_2\left(\frac{π+2\sin^{-1}\left(\frac{3-x}{7}\right)}{π}\right)$.

Options:

[4, -10]

[-4, 10]

[4, 10]

[-4, -10]

Correct Answer:

[-4, 10]

Explanation:

$f(x)=\log_2\left(\frac{π+2\sin^{-1}\left(\frac{3-x}{7}\right)}{π}\right)$

Least value of $2 \sin^{-1}\left(\frac{3-x}{7}\right)$ is '-2' for which $\frac{π+2\sin^{-1}\left(\frac{3-x}{7}\right)}{π}$ is positive. 

So, for domain we must have $-1≤\frac{3-x}{7}≤1$

$∴-7≤3-x≤7$

$⇒-10≤-x≤4$

$⇒-4≤x≤10$

Thus, domain of f(x) is [-4, 10].