1.Relation and Function
hard

यदि फलन $f( x )=\frac{\cos ^{-1} \sqrt{ x ^{2}- x +1}}{\sqrt{\sin ^{-1}\left(\frac{2 x -1}{2}\right)}}$ का प्रान्त, अन्तराल $(\alpha, \beta]$ है, तो $\alpha+\beta$ बराबर है -

A

$2$

B

$\frac{3}{2}$

C

$\frac{1}{2}$

D

$1$

(JEE MAIN-2021)

Solution

$0 \leq x^{2}-x+1 \leq 1$

$\Rightarrow x^{2}-x \leq 0$

$\Rightarrow x \in[0,1]$

$\text { Also, } 0\,<\,\sin ^{-1}\left(\frac{2 x-1}{2}\right) \leq \frac{\pi}{2}$

$\Rightarrow 0\,<\,\frac{2 x-1}{2} \leq 1$

$\Rightarrow 0\,<\,2 x-1 \leq 2$

$1\,<\,2 x \leq 3$

$\frac{1}{2}\,<\,x \leq \frac{3}{2}$

Taking intersection

$x \in\left(\frac{1}{2}, 1\right]$

$\Rightarrow \alpha=\frac{1}{2}, \beta=1$

$\Rightarrow \alpha=\frac{1}{2}, \beta=1$

Standard 12
Mathematics

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