||'''Book'''|| Advanced Engineering Mathematics ||
 ||'''Author'''|| Erwin Kreyszig ||
 ||'''Edition'''|| 8th Edition ||

/* code_begins */

{{{
#2.13-6
x=var('x')
y=function('y',x)
de=diff(y,x,2)+diff(y,x,1)+y==cos(x)+13*cos(2*x)
desolve(de,y)
}}}

/* code_ends */

 * '''Solution by''': 
   *K B Patil,Lecture,SIGCOE NAVI MUMBAI.