If the characteristic equation has roots r=0,0r = 0, 0r=0,0, the general solution is:
y=C1+C2xy = C_1 + C_2 xy=C1+C2x
y=C1ex+C2exy = C_1 e^x + C_2 e^xy=C1ex+C2ex
y=C1x2y = C_1 x^2y=C1x2
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