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Vector Algebra

Question
CBSEENMA12036039

Let y(x) be the solution of the differential equation left parenthesis straight x space log space straight x right parenthesis dy over dx space plus straight y space equals space 2 space straight x space log space straight x comma (x  ≥1). Then, y (e) is equal to 

  • e

  • 0

  • 2

  • 2e

Solution

C.

2

Given differential equation is 
straight x left parenthesis log space straight x right parenthesis dy over dx space plus straight y space equals 2 space straight x space log space straight x comma
rightwards double arrow space dy over dx space plus fraction numerator straight y over denominator straight x space log space straight x end fraction space equals 2
This is a linear differential equation.
therefore,IF space equals space straight e to the power of integral fraction numerator 1 over denominator straight x space log space straight x end fraction dx end exponent space equals space straight e to the power of log space left parenthesis log space straight x right parenthesis space end exponent space equals space log space straight x
Now, the solution of given differential equation is given by
straight y. space log space straight x space equals space integral log space straight x. space 2 dx
straight y. space log space straight x space equals space space equals space 2 integral log space straight x space dx
At space straight y. space log space straight x space equals space 2 left square bracket space straight x space log space straight x minus straight x right square bracket plus straight c
straight x space equals space 1
straight c space equals 2
straight y. space log space straight x space equals space 2 left square bracket straight x space log space straight x minus straight x right square bracket plus 2
straight x space equals straight e
straight y space equals space 2 space left parenthesis straight e minus straight e right parenthesis space plus 2 space rightwards double arrow straight y space equals space 2