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Application Of Derivatives

Question
CBSEENMA12035609

Use differentials, find the approximate value of each of the following upto 3 places of decimal:
left parenthesis 33 right parenthesis to the power of negative 1 fifth end exponent

Solution
left parenthesis 33 right parenthesis to the power of negative 1 fifth end exponent space equals space fraction numerator 1 over denominator left parenthesis 33 right parenthesis to the power of begin display style 1 fifth end style end exponent end fraction
Let space space straight y space equals space straight f left parenthesis straight x right parenthesis space equals space straight x to the power of 1 fifth end exponent comma space space space space straight x space equals space 32 comma space space space dx space equals space 1
   straight f left parenthesis straight x plus increment straight x right parenthesis space equals space left parenthesis 33 right parenthesis to the power of 1 fifth end exponent space equals space straight f left parenthesis straight x right parenthesis space plus space increment straight y space equals space 2 space plus space dy over dx cross times dy
space space space space space space space space space space space space space space space space space space equals space 2 plus fraction numerator 1 over denominator 5 straight x to the power of begin display style 4 over 5 end style end exponent end fraction cross times 1 space equals space 2 plus fraction numerator 1 over denominator 5 space cross times space left parenthesis 32 right parenthesis to the power of begin display style 4 over 5 end style end exponent end fraction
space space space space space space space space space space space space space space space space equals 2 plus fraction numerator 1 over denominator 5 space cross times space 16 end fraction space equals space 2 plus 1 over 80 space equals space 161 over 80
space space space space space space space space space space space space space space space space open parentheses 1 over 33 close parentheses to the power of 1 fifth end exponent space equals fraction numerator 1 over denominator left parenthesis 33 right parenthesis to the power of begin display style 1 fifth end style end exponent end fraction space equals fraction numerator 1 over denominator begin display style 161 over 80 end style end fraction space equals space 80 over 161 space equals space 0.4968 space equals space 0.497