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Differential Equations

Question
CBSEENMA12033155

Solve the differential equation:
straight x dy over dx minus straight y minus 2 straight x cubed space equals space 0.

Solution
The given differential equation is
straight x dy over dx minus straight y minus 2 straight x cubed space equals space 0
or       straight x dy over dx minus straight y space equals space 2 straight x cubed
or        dy over dx minus 1 over straight x. space straight y space equals space 2 straight x squared
Comparing it with  dy over dx plus Py space equals straight Q comma space space we space get comma space straight P space equals space minus 1 over straight x comma space space straight Q space equals space 2 straight x squared
            integral Pdx space equals space minus integral 1 over straight x dx space equals space minus log space straight x space equals space log space straight x to the power of negative 1 end exponent
therefore space space space straight e to the power of integral Pdx end exponent space equals space straight e to the power of log space straight x to the power of negative 1 end exponent end exponent space equals space straight x to the power of negative 1 end exponent space equals space 1 over straight x
therefore    solution of differential equation is
                        straight y. space straight e to the power of integral straight P space dx end exponent space equals space integral straight Q. space straight e to the power of integral straight P space dx end exponent dx plus straight c
or       straight y.1 over straight x space equals space integral 2 space straight x squared. space 1 over straight x dx space plus space straight c space space space space space space or space space space straight y over straight x space equals space 2 integral straight x space dx space plus space straight c
or      straight y over straight x space equals space straight x squared plus straight c       or        straight y space equals space straight x cubed plus cx
                

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