If $\mathrm{f}(\mathrm{x})=[\mathrm{x}]$, for $\mathrm{x} \in(-1,2)$, then $\mathrm{f}$ is discontinuous at…

If $\mathrm{f}(\mathrm{x})=[\mathrm{x}]$, for $\mathrm{x} \in(-1,2)$, then $\mathrm{f}$ is discontinuous at (where $[\mathrm{x}]$ represents floor function)
  1. $\mathrm{x}=-1,0,1,2$
  2. $\mathrm{x}=-1,0,1$
  3. $\mathrm{x}=0,1$
  4. $\mathrm{x}=2$

Solution

We have $\mathrm{f}(\mathrm{x})=[\mathrm{x}]$ Let $[\mathrm{x}]=\mathrm{K}$, an integer. $\therefore \lim _{x \rightarrow K^{+}} f(x)=K \text { and } \lim _{x \rightarrow K^{-}} f(x)=K-1$ Thus given function is not continuous at all integral values in its domain. $\because \mathrm{f}$ is discontinuous at $\mathrm{x}=0,1$.

Asked in: MHT CET 2021 (20 Sep Shift 1)

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