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If F : R → R is Given by F ( X ) = X 3 + 3 , Then F − 1 ( X ) is Equal to (A) X 1 / 3 − 3 (B) X 1 / 3 + 3 (C) ( X − 3 ) 1 / 3 (D) X + 3 1 / 3

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Question

If \[f : R \to R\] is given by \[f\left( x \right) = x^3 + 3, \text{then} f^{- 1} \left( x \right)\] is equal to

 

Options

  •  \[x^{1/3} - 3\]

  •  \[x^{1/3} + 3\]

  • \[\left( x - 3 \right)^{1/3}\]

  • \[x + 3^{1/3}\]

MCQ
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Solution

(c)  \[\text{Let} f^{- 1} \left( x \right) = y\] 
\[f\left( y \right) = x\] 
\[ \Rightarrow y^3 + 3 = x\] 
\[ \Rightarrow y^3 = x - 3\] 
\[ \Rightarrow y = \sqrt[3]{x - 3} \] 
\[ \Rightarrow y = \left( x - 3 \right)^\frac{1}{3} \]

So, the answer is (c). 

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Chapter 2: Functions - Exercise 2.6 [Page 79]

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R.D. Sharma Mathematics Volume 1 and 2 [English] Class 12
Chapter 2 Functions
Exercise 2.6 | Q 47 | Page 79

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