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M-II

Unit-2Linear differential equations Q1) Solve (4D² +4D -3)y =   

S1) Auxiliary equation is 4m² +4m – 3 = 0

    We get,             (2m+3)(2m – 1) = 0

                               m =   ,

complementary function:  CF is  A+ B

now we will find particular integral,

                         P.I. = f(x)

=   .

=    .

=    .

=   . =   .

 General solution is y =  CF + PI

                                                    = A+ B  .

 Q2) Solve

S2) Auxiliary equation are

 Q3)

 

S3) Auxiliary equation are

 Q4) Solve

S4) The AE is

Complete solution y= CF + PI

  Q5) Solve 

S5) The AE is

Complete solutio0n is y= CF + PI

 Q6) solve

S6) Given equation in symbolic form is

Its Auxiliary equation is

Complete solution is y= CF + PI

 

   Q7) Find the PI of(D2-4D+3)y=ex cos2x 

S7)

  Q8) Solve (D2 -5D+6) y = sin 3x

S8)

Auxiliary equation

C.F is

 

 

  

    []

  

  

   The Complete Solution is  

 

 Q9) Solve

S9)

The Auxiliary equation is   

  The C.F is

P.I

Now, 

 

   The Complete Solution is

  Q10) Solve (D2-6D+9) y = e3x (1+x)

S10)

The auxiliary equation is     

The C.F is

But

   The Complete Solution is

   Q11) Solve the following by using the method of variation of parameters.

S11) This can be written as-

C.F.-

Auxiliary equation is-

So that the C.F. will be-

P.I.-

Here

Now

Thus PI = 

            = 

            = 

So that the complete solution is-

 Q12) Solve

S12) On putting so that,

and

The given equation becomes-

Or it can be written as-

So that the auxiliary equation is-

C.F. =

Particular integral-

Where

It’s a Leibnitz’s linear equation having I.F.=

Its solution will be-

P.I. =

       =

So that the complete solution is-

 Q13) Express in terms of Legendre polynomials.

S13)

By equating the coefficients of like powers of x, we get-

Put these values in equation (1), we get-

   Q14)Prove that-

A14) By using Rodrigue formula for Legendre function.

On integrating by parts, we get-

Now integrating m – 2 times, we get-