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Please Solve RD Sharma Class 12 Chapter 17 Maxima and Minima Exercise Case Study Based Questions question 5 subquestion (iv)  Maths Textbook Solution.

Answers (1)

Answer:  x = 2

Hint:  use the concept of maxima and minima.

Solution:

As we know,

C^{\prime}(x)=3600\left(1-\frac{4}{x^{2}}\right)

 Putting   c^{\prime}(x)=0

\begin{aligned} 3600\left(1-\frac{4}{x^{2}}\right) &=0 . \\ \end{aligned}

1-\frac{4}{x^{2}} =0 \\

\frac{x^{2}-4}{x^{2}} =0 \\

x^{2}-4=0 \\

(x-2)(x+2) =0

\begin{aligned} &\mathrm{x}=2 \\ \end{aligned}

\mathrm{c}^{\prime \prime}(\mathrm{x})=3600\left(0-4(-2) \mathrm{x}^{-2-1}\right) \\

\quad=3600(0-4(-2) \mathrm{x}^{-3} \\

=3600\left(8 \mathrm{x}^{-3}\right) \\

=28800 \mathrm{x}^{-3} \\

=\frac{28800}{\mathrm{x}^{3}}

Putting  \begin{aligned} &\mathrm{x}=2 \\ \end{aligned}

\begin{aligned} &c^{\prime \prime}(2)=\frac{28800>0}{(2)^{3}} \\ &c^{\prime \prime}(2)>0 \end{aligned}

So minimum is \begin{aligned} &\mathrm{x}=2 \\ \end{aligned}

 

 

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infoexpert27

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