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Differential Equations

Question
CBSEENMA12033094

Solve the following differential equation:
dy over dx plus 1 space equals space straight e to the power of straight x plus straight y end exponent


Solution
The given differential equation is
               dy over dx plus 1 space equals straight e to the power of straight x plus straight y end exponent                           ...(1)
Put straight x plus straight y space equals straight t comma space space space space space space space space space space space therefore space space space space 1 plus dy over dx equals space dt over dx space space or space space space dy over dx space equals dt over dx minus 1
therefore space space space from space left parenthesis 1 right parenthesis comma space space dt over dx minus 1 plus 1 space equals space straight e to the power of straight t space space space space space or space space space dt over dx space equals straight e to the power of straight t
rightwards double arrow space space space space 1 over straight e to the power of straight t dt space equals space dx space space space rightwards double arrow space space space integral straight e to the power of negative straight t end exponent space dt space equals space integral 1. space dx
therefore space space space space space space space space space space fraction numerator straight e to the power of negative straight t end exponent over denominator negative 1 end fraction space equals space straight x plus straight c space space space space rightwards double arrow space space space minus straight e to the power of negative left parenthesis straight x plus straight y right parenthesis end exponent space equals space straight x space plus straight c space space which space is space required space solution. space space
space

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