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For each t \epsilon R, let [t] be the greatest integer less than or equal to t. Then


\lim_{x\rightarrow 0}x\left ( \left [1/x\right ]\left +[2/x \right ]\left+ .....+[15/x \right ] \right ) 
      
      
 

  • Option 1)

    does not exist (in R).

  • Option 2)

    is equal to 0.

  • Option 3)

    is equal to 15

  • Option 4)

    is equal to 120

 

Answers (2)

best_answer

As we learnt in

The SANDWICH THEOREM -

If \:\:f(x)\leq g(x)\leq h(x)\:\:for\:every\:(x)\:in\:the\:deleted\:neighbourhood\:of\:(a).


and\:\:\:\lim_{x\rightarrow a}\:\:f(x)=\lim_{x\rightarrow a}\:\:h(x)=l


Then\;\:\lim_{x\rightarrow a}\:g(x)\:\:is\:also\:equal\:to\:l

- wherein

 

Where\:\:\:x\epsilon \:(a-\delta ,\:a+\delta )\:\:and\:\:\delta\: \:is\:very\:small.

 

x-1 < \left [ x \right ]\leq x

1/x-1 < \left [ 1/x \right ]\leq 1/x

2/x-1 < \left [ 2/x \right ]\leq 2/x

.

.

.

.

15/x-1 < \left [ 15/x \right ]\leq 15/x

ADD ALL ;

120/x- 15< f(n)\leq 120/x

120-15x/x< f(n)\leq 120/x

\lim_{x\rightarrow 0^{+}} (\frac{120-15x}{x})< \lim_{x\rightarrow 0^{+}}f(x)\leq \lim_{x\rightarrow 0^{+} } 120/x

\lim_{x\rightarrow 0^{+}} 120 -15x< \lim_{x\rightarrow 0^{+}}f(x)\leq 120

Thus \lim_{x\rightarrow 0}f(x)=120


 


Option 1)

does not exist (in R).

Option 2)

is equal to 0.

Option 3)

is equal to 15

Option 4)

is equal to 120

Posted by

Himanshu

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