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Application Of Derivatives

Question
CBSEENMA12035580

Use differentials to approximate square root of 25.3 end root.

Solution

Take      straight y equals space square root of straight x comma space space space straight x space equals space 25 space comma space space space dx space equals space δx equals space 0.3 space space so space that space straight x plus δx space equals space 25.3
Then       δy space equals space square root of 25.3 end root space minus space square root of 25                                       open square brackets because space space space δy space equals space square root of straight x plus δx end root space minus square root of straight x close square brackets space
therefore space space space space square root of 25.3 end root space space equals space 5 space plus space δy                                                                     ...(1)
Now, δy is approximately equal to dy and
  dy space equals dy over dx dx space equals space fraction numerator 1 over denominator 2 square root of straight x end fraction left parenthesis 0.3 right parenthesis space equals space fraction numerator 1 over denominator 2 square root of 25 end fraction left parenthesis 0.3 right parenthesis space equals space fraction numerator 0.3 over denominator 10 end fraction space equals space 0.03
therefore space space space from space left parenthesis 1 right parenthesis comma space space space square root of 25.3 end root space equals space 5 plus 0.03 space equals space 5.03

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