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If f ( x ) = 1 1 − x , show that f[f[f(x)]] = x. - Mathematics

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प्रश्न

If  \[f\left( x \right) = \frac{1}{1 - x}\] , show that f[f[f(x)]] = x.

 

 

उत्तर

Given

 \[f\left( x \right) = \frac{1}{1 - x}\] 

Thus,

\[f\left\{ f\left( x \right) \right\} = f\left\{ \frac{1}{1 - x} \right\}\]  

\[= \frac{1}{1 - \frac{1}{1 - x}}\]

\[= \frac{1}{\frac{1 - x - 1}{1 - x}}\]
\[ = \frac{1 - x}{- x}\]
\[ = \frac{x - 1}{x}\]
Again ,
\[f\left[ f\left\{ f\left( x \right) \right\} \right] = f\left[ \frac{x - 1}{x} \right]\]
\[= \frac{1}{1 - \left( \frac{x - 1}{x} \right)}\]
\[ = \frac{1}{\frac{x - x + 1}{x}}\]
\[ = \frac{x}{1}\]
\[ = x\]
Therefore,  f[f{f(x)}] = x.
Hence proved.
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अध्याय 3: Functions - Exercise 3.2 [पृष्ठ ११]

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आरडी शर्मा Mathematics [English] Class 11
अध्याय 3 Functions
Exercise 3.2 | Q 4 | पृष्ठ ११

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