Range of $f(x)=\sin^{-1}\left[x^2+\frac{1}{2}\right]+\cos^{-1}\left[x^2-\frac{1}{2}\right]$ where [.] denotes the greatest integer function, is
Answer & explanation
Correct answer: option 2
$-1≤\left[x^2+\frac{1}{2}\right]≤1$, $-1≤\left[x^2-\frac{1}{2}\right]≤1$
$-1≤\left(x^2+\frac{1}{2}\right)<2$, $-1≤\left(x^2-\frac{1}{2}\right)<2$
$\frac{-3}{2}≤x^2<\frac{3}{2}$, $\frac{-1}{2}≤x^2<\frac{5}{2}$
$⇒0≤x^2<\frac{3}{2}$, $⇒0≤x^2<\frac{5}{2}$
taking intersection
$x^2∈[0,\frac{3}{2})$
as $x^2∈[0,\frac{1}{2})$
$f(x)=\sin^{-1}(0)+\cos^{-1}(-1)=π$
as $x^2∈\left[\frac{1}{2},\frac{3}{2}\right)$
$f(x)=\cos^{-1}(0)+\sin^{-1}(1)=π$
so $f(x)∈\{π\}$