Final answer:
To find the characteristic equation for the associated homogeneous differential equation y''+2y'+y=0, assume a solution of e^rt, leading to the characteristic equation r^2 + 2r + 1 = 0.
Step-by-step explanation:
The characteristic equation for the associated homogeneous equation of the differential equation y''+2y'+y=0 can be found by assuming a solution of the form ert where r is the variable we are solving for. Substituting y = ert into the homogeneous equation gives us r2ert + 2rert + ert = 0. Dividing through by ert, we obtain the characteristic equation r2 + 2r + 1 = 0.