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Let G ( X ) = 1 + X − [ X ] and F ( X ) = ⎧ ⎨ ⎩ − 1 , X < 0 0 , X = 0 , 1 , X > 0 Where [X] Denotes the Greatest Integer Less than Or Equal to X. Then for All X , F ( G ( X ) ) is Equal to

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Question

 Let
\[g\left( x \right) = 1 + x - \left[ x \right] \text{and} f\left( x \right) = \begin{cases}- 1, & x < 0 \\ 0, & x = 0, \\ 1, & x > 0\end{cases}\] where [x] denotes the greatest integer less than or equal to x. Then for all \[x, f \left( g \left( x \right) \right)\] is equal to

Options

  • x

  • 1

  • f(x)

  •  g(x)

MCQ
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Solution

(b) 1 \[\text{When}, - 1 < x < 0\] 
\[\text{Then}, g(x) = 1 + x - \left[ x \right]\] 
\[ = 1 + x - \left( - 1 \right) = 2 + x\] 
\[ \therefore f\left( g(x) \right) = 1 \] 
\[\text{When}, x = 0\] 
\[\text{Then}, g(x) = 1 + x - \left[ x \right]\] 
  \[ = 1 + x - 0 = 1 + x\] 
\[ \therefore f\left( g(x) \right) = 1\] 
\[\text{When}, x > 1\] 
\[\text{Then}, g(x) = 1 + x - \left[ x \right]\] 
 \[ = 1 + x - 1 = x\] 
\[ \therefore f\left( g(x) \right) = 1\]

Therefore, for each interval f(g(x)) =1

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Chapter 2: Functions - Exercise 2.6 [Page 78]

APPEARS IN

R.D. Sharma Mathematics Volume 1 and 2 [English] Class 12
Chapter 2 Functions
Exercise 2.6 | Q 39 | Page 78

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