MapleUndCoeffEx.mws

>    f:=A*x*exp(x)+B*x*sin(x)+C*x*cos(x);

>   

f := A*x*exp(x)+B*x*sin(x)+C*x*cos(x)

>    diff(f,x,x,x)-diff(f,x,x)+diff(f,x)-f;

2*A*exp(x)-2*B*sin(x)-2*C*cos(x)-2*B*cos(x)+2*C*sin(x)

>    solve({2*A=2,-2*B+2*C=0,-2*C-2*B=-1},{A,B,C});

{A = 1, B = 1/4, C = 1/4}

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