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 Page 1


Edurev123 
6. Second Order Linear Equations with 
Variable Coefficient 
6.1 Solve the ordinary differential equation 
?? (?? -?? )?? '
-(?? ?? -?? )?? +?? ?? =?? ?? (?? ?? -?? ) 
(2012: 20 marks) 
Solution: 
The given equation is : 
           ?? (?? -1)?? '
-(2?? -1)?? +2?? =?? 2
(2?? -3)
?                                   ?? ''
-
(2?? -1)
?? (?? -1)
?? '
+
2?? ?? (?? -1)
 =
?? 2
(2?? -3)
?? (?? -1)
                                         (??)
 
which is of the form of 
?? ''
+???? +???? =?? ?? =
-(2?? -1)
?? (?? -1)
,?? =
2
?? '
(?? -1)
2+2???? +?? ?? 2
 =2+2?? ·
[-(2?? -1)]
?? (?? -1)
+?? 2
·
2
?? (?? -1)
=0
 
?4=?? 2
 is a part of the complementary function. 
Also                        ?? = Second part of ?? .?? . 
 =?? ? 
?? -? ?????? ?? 2
????
 =?? 2
? 
1
?? 4
?? ? 
2?? -1
?? (?? -1)
????
???? =?? 2
? 
1
?? 4
·?? ? (
1
?? +
1
?? -1
)????
?? ?? =?? 2
? 
1
?? 4
·(?? 2
-?? )???? =?? 2
? (
1
?? 2
-
1
?? 3
)????
 =?? 2
(
?? -1
-1
-
?? -2
-2
)
 =-?? +2
 
So, the complementary function is 
?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? where ?? 1
,?? 2
 and ?? 3
 are arbitrary constants.  
Particular integral is 
Page 2


Edurev123 
6. Second Order Linear Equations with 
Variable Coefficient 
6.1 Solve the ordinary differential equation 
?? (?? -?? )?? '
-(?? ?? -?? )?? +?? ?? =?? ?? (?? ?? -?? ) 
(2012: 20 marks) 
Solution: 
The given equation is : 
           ?? (?? -1)?? '
-(2?? -1)?? +2?? =?? 2
(2?? -3)
?                                   ?? ''
-
(2?? -1)
?? (?? -1)
?? '
+
2?? ?? (?? -1)
 =
?? 2
(2?? -3)
?? (?? -1)
                                         (??)
 
which is of the form of 
?? ''
+???? +???? =?? ?? =
-(2?? -1)
?? (?? -1)
,?? =
2
?? '
(?? -1)
2+2???? +?? ?? 2
 =2+2?? ·
[-(2?? -1)]
?? (?? -1)
+?? 2
·
2
?? (?? -1)
=0
 
?4=?? 2
 is a part of the complementary function. 
Also                        ?? = Second part of ?? .?? . 
 =?? ? 
?? -? ?????? ?? 2
????
 =?? 2
? 
1
?? 4
?? ? 
2?? -1
?? (?? -1)
????
???? =?? 2
? 
1
?? 4
·?? ? (
1
?? +
1
?? -1
)????
?? ?? =?? 2
? 
1
?? 4
·(?? 2
-?? )???? =?? 2
? (
1
?? 2
-
1
?? 3
)????
 =?? 2
(
?? -1
-1
-
?? -2
-2
)
 =-?? +2
 
So, the complementary function is 
?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? where ?? 1
,?? 2
 and ?? 3
 are arbitrary constants.  
Particular integral is 
?? ?? =
1
(?? 3
-?? 2
)
(12?? 2
+6?? )
 =
-1
?? 2
(1-?? )
(12?? 2
+6?? )
 =
-1
?? 2
(1-?? )
-1
(12?? 2
+6?? )
 =
-1
?? 2
(1+?? +?? 2
+?.)(12?? 2
+6?? )
 =
-1
?? 2
(12?? 2
+30?? +30)
 =
-1
?? (4?? 3
+15?? 2
+30?? )
 =-(?? 4
+5?? 3
+15?? 2
)
 
? The required general solution is : 
?? =?? ?? +?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? -(?? 4
+5?? 3
+15?? 2
)
 
Particular integral, 
                                           P.I. =?? ?
?? -??????? ?? 2
(??? 4
?? -??????? ???? )???? 
 
 =?? 2
? 
(?? 2
-?? )
?? 4
(? 
?? (2?? -3)
(?? -1)
·?? (?? -1)???? )???? [??? -? ?????? =?? (1)
1]
 =?? 2
? 
?? 2
-?? ?? 4
[? ?? 2
(2?? -3)???? ]????
 =?? 2
? 
?? -1
?? 3
[? (2?? 3
-3?? 2
)???? ]????
 =
?? 2
2
? (?? -1)(?? -2)????
 =
?? 2
2
? (?? 2
-3?? -2)???? =
?? 2
2
(
?? 3
3
-
3?? 2
2
+2?? )
 
? Complete solution of (i) is 
?? =?? 1
?? 2
+?? 2
(2-?? )+
?? 2
2
(
?? 3
3
-
3?? 2
2
+2?? ) 
6.2 Find the general solution of the equation: 
?? ?? ?? ?? ?? ?? ?? ?? +?? ????
????
+?? =???? ?? ?????? (???? ?? ) 
(2013: 15 Marks) 
Page 3


Edurev123 
6. Second Order Linear Equations with 
Variable Coefficient 
6.1 Solve the ordinary differential equation 
?? (?? -?? )?? '
-(?? ?? -?? )?? +?? ?? =?? ?? (?? ?? -?? ) 
(2012: 20 marks) 
Solution: 
The given equation is : 
           ?? (?? -1)?? '
-(2?? -1)?? +2?? =?? 2
(2?? -3)
?                                   ?? ''
-
(2?? -1)
?? (?? -1)
?? '
+
2?? ?? (?? -1)
 =
?? 2
(2?? -3)
?? (?? -1)
                                         (??)
 
which is of the form of 
?? ''
+???? +???? =?? ?? =
-(2?? -1)
?? (?? -1)
,?? =
2
?? '
(?? -1)
2+2???? +?? ?? 2
 =2+2?? ·
[-(2?? -1)]
?? (?? -1)
+?? 2
·
2
?? (?? -1)
=0
 
?4=?? 2
 is a part of the complementary function. 
Also                        ?? = Second part of ?? .?? . 
 =?? ? 
?? -? ?????? ?? 2
????
 =?? 2
? 
1
?? 4
?? ? 
2?? -1
?? (?? -1)
????
???? =?? 2
? 
1
?? 4
·?? ? (
1
?? +
1
?? -1
)????
?? ?? =?? 2
? 
1
?? 4
·(?? 2
-?? )???? =?? 2
? (
1
?? 2
-
1
?? 3
)????
 =?? 2
(
?? -1
-1
-
?? -2
-2
)
 =-?? +2
 
So, the complementary function is 
?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? where ?? 1
,?? 2
 and ?? 3
 are arbitrary constants.  
Particular integral is 
?? ?? =
1
(?? 3
-?? 2
)
(12?? 2
+6?? )
 =
-1
?? 2
(1-?? )
(12?? 2
+6?? )
 =
-1
?? 2
(1-?? )
-1
(12?? 2
+6?? )
 =
-1
?? 2
(1+?? +?? 2
+?.)(12?? 2
+6?? )
 =
-1
?? 2
(12?? 2
+30?? +30)
 =
-1
?? (4?? 3
+15?? 2
+30?? )
 =-(?? 4
+5?? 3
+15?? 2
)
 
? The required general solution is : 
?? =?? ?? +?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? -(?? 4
+5?? 3
+15?? 2
)
 
Particular integral, 
                                           P.I. =?? ?
?? -??????? ?? 2
(??? 4
?? -??????? ???? )???? 
 
 =?? 2
? 
(?? 2
-?? )
?? 4
(? 
?? (2?? -3)
(?? -1)
·?? (?? -1)???? )???? [??? -? ?????? =?? (1)
1]
 =?? 2
? 
?? 2
-?? ?? 4
[? ?? 2
(2?? -3)???? ]????
 =?? 2
? 
?? -1
?? 3
[? (2?? 3
-3?? 2
)???? ]????
 =
?? 2
2
? (?? -1)(?? -2)????
 =
?? 2
2
? (?? 2
-3?? -2)???? =
?? 2
2
(
?? 3
3
-
3?? 2
2
+2?? )
 
? Complete solution of (i) is 
?? =?? 1
?? 2
+?? 2
(2-?? )+
?? 2
2
(
?? 3
3
-
3?? 2
2
+2?? ) 
6.2 Find the general solution of the equation: 
?? ?? ?? ?? ?? ?? ?? ?? +?? ????
????
+?? =???? ?? ?????? (???? ?? ) 
(2013: 15 Marks) 
Solution: 
We have 
(?? 2
?? 2
+???? +1)?? =ln ?? sin (ln ?? ) 
This is in the Cauchy-Euler form. 
Let 
?? =ln ?? 
?
????
????
         =
1
?? ??? ?? ????
=
?? ????
?????         =?? 1
 where 
?? ????
=?? 1
 
Similarly, 
?? 2
?? 2
=?? 1
(?? 1
-1) 
? (?? 1
(?? 1
-1)+?? 1
+1)?? =?? sin ?? 
? (?? 1
2
+1)?? =?? sin ?? 
Auxiliary equation is ?? 2
+1=0 
? Comfiementary function (C.F.) 
?? =±?? =?? 1
cos ?? +?? 2
sin ?? P.I.  =
1
(?? 2
+1)
?? sin ?? = Real part 
1
?? 2
+1
?? ?? ????
 
Now, 
1
?? 2
+1
?? ?? ????
 =?? ????
1
(?? +??)
2
+1
?? =?? ????
1
?? 2
+2????
?? =
?? ????
2?? 1
?? (1+
?? 2?? )
-1
?? =
?? ????
2?? ·
1
?? (1-
?? 2?? +
?? 2
4?? 2
)?? 
Page 4


Edurev123 
6. Second Order Linear Equations with 
Variable Coefficient 
6.1 Solve the ordinary differential equation 
?? (?? -?? )?? '
-(?? ?? -?? )?? +?? ?? =?? ?? (?? ?? -?? ) 
(2012: 20 marks) 
Solution: 
The given equation is : 
           ?? (?? -1)?? '
-(2?? -1)?? +2?? =?? 2
(2?? -3)
?                                   ?? ''
-
(2?? -1)
?? (?? -1)
?? '
+
2?? ?? (?? -1)
 =
?? 2
(2?? -3)
?? (?? -1)
                                         (??)
 
which is of the form of 
?? ''
+???? +???? =?? ?? =
-(2?? -1)
?? (?? -1)
,?? =
2
?? '
(?? -1)
2+2???? +?? ?? 2
 =2+2?? ·
[-(2?? -1)]
?? (?? -1)
+?? 2
·
2
?? (?? -1)
=0
 
?4=?? 2
 is a part of the complementary function. 
Also                        ?? = Second part of ?? .?? . 
 =?? ? 
?? -? ?????? ?? 2
????
 =?? 2
? 
1
?? 4
?? ? 
2?? -1
?? (?? -1)
????
???? =?? 2
? 
1
?? 4
·?? ? (
1
?? +
1
?? -1
)????
?? ?? =?? 2
? 
1
?? 4
·(?? 2
-?? )???? =?? 2
? (
1
?? 2
-
1
?? 3
)????
 =?? 2
(
?? -1
-1
-
?? -2
-2
)
 =-?? +2
 
So, the complementary function is 
?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? where ?? 1
,?? 2
 and ?? 3
 are arbitrary constants.  
Particular integral is 
?? ?? =
1
(?? 3
-?? 2
)
(12?? 2
+6?? )
 =
-1
?? 2
(1-?? )
(12?? 2
+6?? )
 =
-1
?? 2
(1-?? )
-1
(12?? 2
+6?? )
 =
-1
?? 2
(1+?? +?? 2
+?.)(12?? 2
+6?? )
 =
-1
?? 2
(12?? 2
+30?? +30)
 =
-1
?? (4?? 3
+15?? 2
+30?? )
 =-(?? 4
+5?? 3
+15?? 2
)
 
? The required general solution is : 
?? =?? ?? +?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? -(?? 4
+5?? 3
+15?? 2
)
 
Particular integral, 
                                           P.I. =?? ?
?? -??????? ?? 2
(??? 4
?? -??????? ???? )???? 
 
 =?? 2
? 
(?? 2
-?? )
?? 4
(? 
?? (2?? -3)
(?? -1)
·?? (?? -1)???? )???? [??? -? ?????? =?? (1)
1]
 =?? 2
? 
?? 2
-?? ?? 4
[? ?? 2
(2?? -3)???? ]????
 =?? 2
? 
?? -1
?? 3
[? (2?? 3
-3?? 2
)???? ]????
 =
?? 2
2
? (?? -1)(?? -2)????
 =
?? 2
2
? (?? 2
-3?? -2)???? =
?? 2
2
(
?? 3
3
-
3?? 2
2
+2?? )
 
? Complete solution of (i) is 
?? =?? 1
?? 2
+?? 2
(2-?? )+
?? 2
2
(
?? 3
3
-
3?? 2
2
+2?? ) 
6.2 Find the general solution of the equation: 
?? ?? ?? ?? ?? ?? ?? ?? +?? ????
????
+?? =???? ?? ?????? (???? ?? ) 
(2013: 15 Marks) 
Solution: 
We have 
(?? 2
?? 2
+???? +1)?? =ln ?? sin (ln ?? ) 
This is in the Cauchy-Euler form. 
Let 
?? =ln ?? 
?
????
????
         =
1
?? ??? ?? ????
=
?? ????
?????         =?? 1
 where 
?? ????
=?? 1
 
Similarly, 
?? 2
?? 2
=?? 1
(?? 1
-1) 
? (?? 1
(?? 1
-1)+?? 1
+1)?? =?? sin ?? 
? (?? 1
2
+1)?? =?? sin ?? 
Auxiliary equation is ?? 2
+1=0 
? Comfiementary function (C.F.) 
?? =±?? =?? 1
cos ?? +?? 2
sin ?? P.I.  =
1
(?? 2
+1)
?? sin ?? = Real part 
1
?? 2
+1
?? ?? ????
 
Now, 
1
?? 2
+1
?? ?? ????
 =?? ????
1
(?? +??)
2
+1
?? =?? ????
1
?? 2
+2????
?? =
?? ????
2?? 1
?? (1+
?? 2?? )
-1
?? =
?? ????
2?? ·
1
?? (1-
?? 2?? +
?? 2
4?? 2
)?? 
 =
?? ????
2?? 1
?? (?? -
1
2?? )=
?? ????
2?? (
?? 2
2
-
?? 2?? )
 =
?? ????
4
(-???? 2
+?? )
?  R.P. of 
1
?? 2
+1
?? ?? ????
 = R.P. of {
?? ????
4
(-???? 2
+?? )}
 =
1
4
(?? cos ?? +?? 2
sin ?? )
? ???? =
1
4
(?? cos ?? +?? 2
sin ?? )
?? =?? 1
cos ?? +?? 2
sin ?? +
?? 4
cos ?? +
?? 2
4
sin ?? =(?? 1
+
ln ?? 4
)cos (ln ?? )+{?? 2
+
(ln ?? )
2
4
}sin (ln ?? )
 
6.3 Solve the differential equation: 
?? ?? ?? ?? ?? ?? ?? ?? +?? ?? ?? ?? ?? ?? ?? ?? ?? +?? ????
????
+?? ?? =???? ?????? (??????
?? ?? ) 
(2014 : 20 Marks) 
Solution: 
Given that 
(?? 3
?? 3
+3?? 2
?? 2
+???? +8)?? =65cos log ?? (??) 
??????                                                                   ?? =?? ?? 
                                                              
?                                                                 log ?? =?? 
?????? ??????                                                             ?? 1
=
?? ????
 
Then 
2?? =?? 1
 and ?? 2
?? 2
=?? 1
(?? 1
-1)
?? 3
 =?? 1
(?? 1
-1)(?? 1
-2)
 
? (i), we have 
(?? 1
(?? 1
-1)(?? 1
-2)+3(?? 1
)(?? 1
-1)+?? 1
+8)?? =65cos ?? 
?                                                                      (?? 1
3
+8)?? =65cos??                                           (???? ) 
Auxiliary equation of (ii) is 
Page 5


Edurev123 
6. Second Order Linear Equations with 
Variable Coefficient 
6.1 Solve the ordinary differential equation 
?? (?? -?? )?? '
-(?? ?? -?? )?? +?? ?? =?? ?? (?? ?? -?? ) 
(2012: 20 marks) 
Solution: 
The given equation is : 
           ?? (?? -1)?? '
-(2?? -1)?? +2?? =?? 2
(2?? -3)
?                                   ?? ''
-
(2?? -1)
?? (?? -1)
?? '
+
2?? ?? (?? -1)
 =
?? 2
(2?? -3)
?? (?? -1)
                                         (??)
 
which is of the form of 
?? ''
+???? +???? =?? ?? =
-(2?? -1)
?? (?? -1)
,?? =
2
?? '
(?? -1)
2+2???? +?? ?? 2
 =2+2?? ·
[-(2?? -1)]
?? (?? -1)
+?? 2
·
2
?? (?? -1)
=0
 
?4=?? 2
 is a part of the complementary function. 
Also                        ?? = Second part of ?? .?? . 
 =?? ? 
?? -? ?????? ?? 2
????
 =?? 2
? 
1
?? 4
?? ? 
2?? -1
?? (?? -1)
????
???? =?? 2
? 
1
?? 4
·?? ? (
1
?? +
1
?? -1
)????
?? ?? =?? 2
? 
1
?? 4
·(?? 2
-?? )???? =?? 2
? (
1
?? 2
-
1
?? 3
)????
 =?? 2
(
?? -1
-1
-
?? -2
-2
)
 =-?? +2
 
So, the complementary function is 
?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? where ?? 1
,?? 2
 and ?? 3
 are arbitrary constants.  
Particular integral is 
?? ?? =
1
(?? 3
-?? 2
)
(12?? 2
+6?? )
 =
-1
?? 2
(1-?? )
(12?? 2
+6?? )
 =
-1
?? 2
(1-?? )
-1
(12?? 2
+6?? )
 =
-1
?? 2
(1+?? +?? 2
+?.)(12?? 2
+6?? )
 =
-1
?? 2
(12?? 2
+30?? +30)
 =
-1
?? (4?? 3
+15?? 2
+30?? )
 =-(?? 4
+5?? 3
+15?? 2
)
 
? The required general solution is : 
?? =?? ?? +?? ?? =?? 1
+?? 2
?? +?? 3
?? ?? -(?? 4
+5?? 3
+15?? 2
)
 
Particular integral, 
                                           P.I. =?? ?
?? -??????? ?? 2
(??? 4
?? -??????? ???? )???? 
 
 =?? 2
? 
(?? 2
-?? )
?? 4
(? 
?? (2?? -3)
(?? -1)
·?? (?? -1)???? )???? [??? -? ?????? =?? (1)
1]
 =?? 2
? 
?? 2
-?? ?? 4
[? ?? 2
(2?? -3)???? ]????
 =?? 2
? 
?? -1
?? 3
[? (2?? 3
-3?? 2
)???? ]????
 =
?? 2
2
? (?? -1)(?? -2)????
 =
?? 2
2
? (?? 2
-3?? -2)???? =
?? 2
2
(
?? 3
3
-
3?? 2
2
+2?? )
 
? Complete solution of (i) is 
?? =?? 1
?? 2
+?? 2
(2-?? )+
?? 2
2
(
?? 3
3
-
3?? 2
2
+2?? ) 
6.2 Find the general solution of the equation: 
?? ?? ?? ?? ?? ?? ?? ?? +?? ????
????
+?? =???? ?? ?????? (???? ?? ) 
(2013: 15 Marks) 
Solution: 
We have 
(?? 2
?? 2
+???? +1)?? =ln ?? sin (ln ?? ) 
This is in the Cauchy-Euler form. 
Let 
?? =ln ?? 
?
????
????
         =
1
?? ??? ?? ????
=
?? ????
?????         =?? 1
 where 
?? ????
=?? 1
 
Similarly, 
?? 2
?? 2
=?? 1
(?? 1
-1) 
? (?? 1
(?? 1
-1)+?? 1
+1)?? =?? sin ?? 
? (?? 1
2
+1)?? =?? sin ?? 
Auxiliary equation is ?? 2
+1=0 
? Comfiementary function (C.F.) 
?? =±?? =?? 1
cos ?? +?? 2
sin ?? P.I.  =
1
(?? 2
+1)
?? sin ?? = Real part 
1
?? 2
+1
?? ?? ????
 
Now, 
1
?? 2
+1
?? ?? ????
 =?? ????
1
(?? +??)
2
+1
?? =?? ????
1
?? 2
+2????
?? =
?? ????
2?? 1
?? (1+
?? 2?? )
-1
?? =
?? ????
2?? ·
1
?? (1-
?? 2?? +
?? 2
4?? 2
)?? 
 =
?? ????
2?? 1
?? (?? -
1
2?? )=
?? ????
2?? (
?? 2
2
-
?? 2?? )
 =
?? ????
4
(-???? 2
+?? )
?  R.P. of 
1
?? 2
+1
?? ?? ????
 = R.P. of {
?? ????
4
(-???? 2
+?? )}
 =
1
4
(?? cos ?? +?? 2
sin ?? )
? ???? =
1
4
(?? cos ?? +?? 2
sin ?? )
?? =?? 1
cos ?? +?? 2
sin ?? +
?? 4
cos ?? +
?? 2
4
sin ?? =(?? 1
+
ln ?? 4
)cos (ln ?? )+{?? 2
+
(ln ?? )
2
4
}sin (ln ?? )
 
6.3 Solve the differential equation: 
?? ?? ?? ?? ?? ?? ?? ?? +?? ?? ?? ?? ?? ?? ?? ?? ?? +?? ????
????
+?? ?? =???? ?????? (??????
?? ?? ) 
(2014 : 20 Marks) 
Solution: 
Given that 
(?? 3
?? 3
+3?? 2
?? 2
+???? +8)?? =65cos log ?? (??) 
??????                                                                   ?? =?? ?? 
                                                              
?                                                                 log ?? =?? 
?????? ??????                                                             ?? 1
=
?? ????
 
Then 
2?? =?? 1
 and ?? 2
?? 2
=?? 1
(?? 1
-1)
?? 3
 =?? 1
(?? 1
-1)(?? 1
-2)
 
? (i), we have 
(?? 1
(?? 1
-1)(?? 1
-2)+3(?? 1
)(?? 1
-1)+?? 1
+8)?? =65cos ?? 
?                                                                      (?? 1
3
+8)?? =65cos??                                           (???? ) 
Auxiliary equation of (ii) is 
?                                              ?? 1
3
+8 =0
?             (?? 1
+2)(?? 1
-2?? 1
+4) =0
 ?? 1
 =-2,1±v3?? ?                                                 C.F.  =?? ?? =?? 1
?? -2?? +?? 2
?? ?? (?? 2
cos v3?? +?? 3
sin v3?? )
 P.I.  =
1
(?? 1
3
+8)
(65cos ?? )
 =
65
-?? 1
+8
cos ?? =
(?? 1
+8)65
-?? 1
2
+64
cos ?? 
                                               =
65
65
(?? 1
+8)cos ??                                               =(?? 1
+8)cos ??                                               =-sin ?? +8cos ?? ?? =?? ?? +?? ?? ?? =?? 1
?? -2?? +?? ?? (?? 2
cos v3?? +?? 3
sin v3?? )-sin ?? +8cos ?? =?? 1
?? -2
+?? (?? 2
cos v3log ?? +?? 3
sin v3log ?? )-sin (log ?? )+8cos (log ?? )
 
which is the required solution. 
6.4 Solve : ?? ?? ?? ?? ?? ?? ?? ?? +?? ?? ?? ?? ?? ?? ?? ?? ?? +?? ?? ?? ?? ?? ?? ?? ?? ?? -?? ?? ????
????
-?? ?? =?? ?? +???????? (?????? ?? ) . 
(2015 : 13 Marks) 
Solution: 
Putting ?? =?? ?? , equation becomes 
[?? (?? -1)(?? -2)(?? -3)+6?? (?? -1)(?? -2)+4?? (?? -1)-2?? -4]=?? 2?? +2cos ?? [?? (?? -1)(?? -2)(?? -3)+6?? (?? -1)(?? -2)+2(?? -2)(?? +1)]=?? 2?? +2cos ?? ?                           (?? 2
+1)(?? 2
-4)?? =?? ?? +2cos ?? 
For homogeneous part 
?? ?? =?? 1
?? 2?? +?? 2
?? -2?? +?? 3
sin ?? +?? 4
cos ?? 
Particular integral 
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