Jee Main Jan 30 Shift 1 Mathematics - Question8
Question 8
The domain of $y=\cos ^{-1}\left|\frac{2-|x|}{4}\right|+(\log (3-x))^{-1}$ is $[-\alpha, \beta)-{\gamma}$, then value of $\alpha+\beta+\gamma=$ ?
(1) 9
(2) 12
(3) 11
(4) 10
Show Answer
Answer: (3)
Solution:
$-1 \leq\left|\frac{2-|x|}{4}\right| \leq 1$
$\Rightarrow\left|\frac{2-|x|}{4}\right| \leq 1$
$\Rightarrow-1 \leq \frac{2-|x|}{4} \leq 1$
$-4 \leq 2-|x| \leq 4$
$-6 \leq-|x| \leq 2$
$-2 \leq|x| \leq 6$
$|x| \leq 6$
$\Rightarrow x \in[-6,6]$
Now, $3-x \neq 1$
And $x \neq 2$
and $3-x>0$
$x<3$
From (1), (2) and (3)
$\Rightarrow x \in[-6,3]-{2}$
$\alpha=6$
$\beta=3$
$\gamma=2$
$\alpha+\beta+\gamma=11$





