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If F is a Real Function Satisfying F ( X + 1 X ) = X 2 + 1 X 2 for All X ∈ R − {0}, Then Write the Expression for F(X). - Mathematics

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Question

If f is a real function satisfying \[f\left( x + \frac{1}{x} \right) = x^2 + \frac{1}{x^2}\]

for all x ∈ R − {0}, then write the expression for f(x).

 
 

Solution

Given:

\[f\left( x + \frac{1}{x} \right) = x^2 + \frac{1}{x^2}\] 

\[= x^2 + \frac{1}{x^2} + 2 - 2\]

\[= \left( x + \frac{1}{x} \right)^2 - 2\]
Thus,
\[f\left( x + \frac{1}{x} \right) = \left( x + \frac{1}{x} \right)^2 - 2\]
Hence,
f (x)  = x-  2 , where | x | ≥  2.
 
 
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Chapter 3: Functions - Exercise 3.5 [Page 41]

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RD Sharma Mathematics [English] Class 11
Chapter 3 Functions
Exercise 3.5 | Q 2 | Page 41

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