For \(f(x)=\frac{\sin \pi[x]}{1+[x]}+\frac{x}{2+3 x}\), where \([x]\) denotes the greatest integer function,…

For \(f(x)=\frac{\sin \pi[x]}{1+[x]}+\frac{x}{2+3 x}\), where \([x]\) denotes the greatest integer function, the domain and range in \(R\) are respectively
  1. \(R-\left\{-1, \frac{-2}{3}\right\}\) and \(R-\left\{\frac{1}{3}\right\}\)
  2. \(\mathrm{R}-\left\{-1, \frac{-2}{3}\right\}\) and \([-1,1]\)
  3. $R-(-1,0)$ and $R-\left\{\frac{1}{3}\right\}$
  4. $R - (-1,0)$ and $(-1,1)$

Solution

As $[x]=-1$ when $x \in[-1,0)$. This makes the denominator of the first part $1+[x]=0$. Hence, the interval $[-1,0)$ must be excluded from the domain set. $\therefore \mathrm{D}(f)=R-[-1,0)$ Also at $x=0$ (which is part of the domain), the value of the function is zero. i.e. $f(0)=0$ So option (d) is correct.

Asked in: AP EAMCET 2020 (17 Sep Shift 2)

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