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The Function F (X) = X − [X], Where [⋅] Denotes the Greatest Integer Function is (A) Continuous Everywhere (B) Continuous at Integer Points Only

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प्रश्न

The function f (x) = x − [x], where [⋅] denotes the greatest integer function is

विकल्प

  • continuous everywhere

  • continuous at integer points only

  • continuous at non-integer points only

  • differentiable everywhere

MCQ
संक्षेप में उत्तर
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उत्तर

(c) continuous at non-integer points only 

\[\text{ We have }, \]
\[f\left( x \right) = x - \left[ x \right]\]
\[\text{Consider n be an integer} . \]

`f(x) = x - [x] = {(x-(n-1),n-1le x <n),(0, x = n),(x-n , n le x < n +1):}`
Now,
\[\left( \text { LHL at x = n } \right) = \lim_{x \to n^-} f\left( x \right) = x - \left( n - 1 \right) = x - n + 1\]
\[\left( \text { RHL at x } = n \right) = \lim_{x \to n^+} f\left( x \right) = x - \left( n \right) = x - n\]
\[\text { As, LHL } \neq\text {  RHL at x } = n\]
\[i . e . , \text{given function is not continuous at n} . \]
\[\text{Now, n is any integer} . \]
\[\text{Therefore, given function is not continuous at integers} . \]

Therefore, given points are continuous at non-integer points only.

 
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अध्याय 9: Differentiability - Exercise 10.4 [पृष्ठ १८]

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आर.डी. शर्मा Mathematics Volume 1 and 2 [English] Class 12
अध्याय 9 Differentiability
Exercise 10.4 | Q 14 | पृष्ठ १८

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