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F(X) = 1 X 2 + 2 . - Mathematics

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Question

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

Sum

Solution

\[\text { Given }: \hspace{0.167em} f\left( x \right) = \frac{1}{x^2 + 2}\]

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

\[\text { For the local maxima or minima, we must have }\]

\[ f'\left( x \right) = 0\]

\[ \Rightarrow \frac{- 2x}{\left( x^2 + 2 \right)^2} = 0\]

\[ \Rightarrow x = 0\]

Now, for values close to x = 0 and to the left of 0,

\[f'\left( x \right) > 0\] .
Also, for values close to x = 0 and to the right of 0, \[f'\left( x \right) < 0\] .
Therefore, by first derivative test, x = 0 is a point of local maxima and the local maximum value of
\[f\left( x \right) \text { is }\frac{1}{2} .\]
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Chapter 18: Maxima and Minima - Exercise 18.2 [Page 16]

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RD Sharma Mathematics [English] Class 12
Chapter 18 Maxima and Minima
Exercise 18.2 | Q 5 | Page 16

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