Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

If f : R → S defined by $f(x)=\sin x-\sqrt{3}\cos x+1$ is onto, then what is the interval of S?

Options:

(–2, 2)

[–2, 2]

[–1, 3]

$[-\sqrt{3},\sqrt{3}]$

Correct Answer:

[–1, 3]

Explanation:

$-\sqrt{1+(-\sqrt{3})^2}≤(\sin x-\sqrt{3}\cos x)≤\sqrt{1+(\sqrt{-3})^2}$

$-2≤(\sin x-\sqrt{3}\cos x)≤2$

$-2+1≤(\sin x-\sqrt{3}\cos x+1)≤2+1$

$-1≤(\sin x-\sqrt{3}\cos x+1)≤3$ i.e.,

Range = [-1, 3]

For f to be onto S = [-1, 3]