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What is the Right Hand limit of the function  \lim _{x \rightarrow-1} \frac{[x]}{x^2+5},   where  [ \, \, ] indicates the Floor Function?

 

Option: 1

\begin{aligned} & \frac{1}{6} \\ \end{aligned}


Option: 2

\begin{aligned} & -\frac{1}{16} \\ \end{aligned}


Option: 3

\begin{aligned} & -\frac{1}{4} \\ \end{aligned}


Option: 4

\begin{aligned} & -\frac{1}{6} \end{aligned}


Answers (1)

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Note that the following essential points.

  • The Right Hand limit of the function at is f(x) \text { at } x=a \text { is } \lim _{x \rightarrow a^{+}} f(x)=\lim _{h \rightarrow 0} f(a+h).

  • The Left Hand limit of the function at is f(x) \text { at } x=a \text { is } \lim _{x \rightarrow a^{+}} f(x)=\lim _{h \rightarrow 0} f(a-h).

  • Here, h is positive and infinitely small.

  • The Floor Function indicates the greatest integer function [GIF] denoted mathematically as [ p ] , for only real values. This function  [p]  rounds downs the real number having any fractional or decimal part (if any) to the nearest integral value less than the indicated number.

For  h\rightarrow 0^{^+} , [-1+h]=-1

The Right Hand limit of the function   \lim _{x \rightarrow-1} \frac{[x]}{x^2+5}   is

\begin{aligned} & \lim _{x \rightarrow-1^{+}} \frac{[x]}{x^2+5} \\ & =\lim _{h \rightarrow 0^{-}} \frac{[-1+h]}{(-1+h)^2+5} \\ & =\lim _{h \rightarrow 0^{-}} \frac{[-1+h]}{1-2 h+h^2+5} \\ & =\frac{-1}{1-0+0+5} \\ & =-\frac{1}{6} \end{aligned}

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Irshad Anwar

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