Question
The domain of $$f\left( x \right) = {\sin ^{ - 1}}\left( {\frac{{1 + {x^2}}}{{2x}}} \right) + \sqrt {1 - {x^2}} \,$$ is :
A.
$$\left\{ 1 \right\}$$
B.
$$\left( { - 1,\,1} \right)$$
C.
$$\left\{ {1,\, - 1} \right\}$$
D.
none of these
Answer :
$$\left\{ {1,\, - 1} \right\}$$
Solution :
Here $$\left| {\frac{{1 + {x^2}}}{{2x}}} \right| \leqslant 1$$ and $$1 - {x^2} \geqslant 0.$$ The first inequality implies $$x=1,\,-1,$$ which satisfy the second inequation.