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Need solution for RD Sharma maths class 12 chapter Maxima and Minima exercise Multiple Choice question, question 20.

Answers (1)

Answer: option(a) 75

Hint: For local maxima or minima, we must have f'(x)=0.

Given: f(x)=x^2+\frac{250}{x}

Solution:

We have,

 f(x)=x^2+\frac{250}{x}

f'(x)=2x-\frac{250}{x^2}                                                   

For maxima and minima f'(x)=0

\Rightarrow 2x-\frac{250}{x^2}=0

\Rightarrow 2x^3=250

\Rightarrow x^3=125

\Rightarrow x=5

Now,

f^{\prime \prime}(x)=2+\frac{500}{x^{3}}=2+\frac{500}{5^{3}}=2+\frac{500}{125}=\frac{750}{125}=6>0

So, x = 5 is a local minima.

f(x)_{min}=(5)^2+\frac{250}{5}=25+50=75

Posted by

infoexpert24

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