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Differential Equations

Question
CBSEENMA12033136

Solve:
straight y space straight e to the power of straight x over straight y end exponent dx space equals open parentheses xe to the power of straight x over straight y end exponent plus straight y squared close parentheses space space dy comma space space space straight y not equal to 0

Solution

The given differential equation is
              straight y space straight e to the power of straight x over straight y end exponent space dx space equals space open parentheses xe to the power of straight x over straight y end exponent plus straight y squared close parentheses space dy
or                dx over dy space equals space fraction numerator xe to the power of begin display style straight x over straight y end style end exponent plus straight y squared over denominator ye to the power of begin display style straight x over straight y end style end exponent end fraction
or                dx over dy space equals fraction numerator xe to the power of begin display style straight x over straight y end style end exponent plus straight y squared over denominator ye to the power of begin display style straight x over straight y end style end exponent end fraction
or                 dx over dy space equals space straight x over straight y plus straight y over straight e to the power of begin display style straight x over straight y end style end exponent                
Put y = v y  so that dx over dy equals straight v plus straight y dv over dx
therefore space space space space space space space space space straight v plus straight y dv over dy space equals space straight v plus ye to the power of negative straight v end exponent
therefore space space space space space space space space straight y dv over dy space equals space straight y space straight e to the power of negative straight v end exponent space space space space space space space space space space space or space space space space space space dv over dy space equals straight e to the power of negative straight v end exponent
Separting the variables and integration, we get,
                  integral straight e to the power of straight v dv space equals space integral dy space space space space space space space space space or space space space space space straight e to the power of straight v space equals space straight y plus straight c
or                          straight e to the power of straight x over straight y end exponent space equals space straight y plus straight c

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