ODE
\[ y'''(x)+2 y''(x)+y'(x)=0 \] ODE Classification
[[_3rd_order, _missing_x]]
Book solution method
TO DO
Mathematica ✓
cpu = 0.0152765 (sec), leaf count = 24
\[\left \{\left \{y(x)\to c_3-e^{-x} \left (c_2 (x+1)+c_1\right )\right \}\right \}\]
Maple ✓
cpu = 0.008 (sec), leaf count = 16
\[ \left \{ y \left ( x \right ) ={{\rm e}^{-x}} \left ( {\it \_C3}\,x+{\it \_C2} \right ) +{\it \_C1} \right \} \] Mathematica raw input
DSolve[y'[x] + 2*y''[x] + y'''[x] == 0,y[x],x]
Mathematica raw output
{{y[x] -> -((C[1] + (1 + x)*C[2])/E^x) + C[3]}}
Maple raw input
dsolve(diff(diff(diff(y(x),x),x),x)+2*diff(diff(y(x),x),x)+diff(y(x),x) = 0, y(x),'implicit')
Maple raw output
y(x) = exp(-x)*(_C3*x+_C2)+_C1