1. Problem: Solve the differential operator equation $$y'' + 2y' - 3y = (3x + 2)e^{-2x}$$ using the differential operator $D = \frac{d}{dx}$.
2. Formula: The operator form is $$(D^2 + 2D - 3)y = (3x + 2)e^{-2x}$$.
3. Step 1: Find the complementary function (CF) by solving the homogeneous equation:
$$D^2 + 2D - 3 = 0$$
Characteristic equation:
$$m^2 + 2m - 3 = 0$$
Factor:
$$(m + 3)(m - 1) = 0$$
So,
$$m = -3, 1$$
CF:
$$y_c = C_1 e^{-3x} + C_2 e^{x}$$
4. Step 2: Find the particular solution (PS) using the method of undetermined coefficients.
Since the right side is $(3x + 2)e^{-2x}$, try:
$$y_p = e^{-2x}(Ax + B)$$
5. Step 3: Compute derivatives:
$$y_p' = e^{-2x}(A - 2Ax - 2B)$$
$$y_p'' = e^{-2x}(-4A + 4Ax + 4B)$$
6. Step 4: Substitute into the left side:
$$y_p'' + 2y_p' - 3y_p = e^{-2x}[-4A + 4Ax + 4B + 2(A - 2Ax - 2B) - 3(Ax + B)]$$
Simplify inside brackets:
$$-4A + 4Ax + 4B + 2A - 4Ax - 4B - 3Ax - 3B = (-4A + 2A) + (4Ax - 4Ax - 3Ax) + (4B - 4B - 3B)$$
$$= -2A - 3Ax - 3B$$
7. Step 5: Equate to right side:
$$-3Ax - 2A - 3B = 3x + 2$$
Match coefficients:
For $x$:
$$-3A = 3 \Rightarrow A = -1$$
For constants:
$$-2A - 3B = 2$$
Substitute $A = -1$:
$$-2(-1) - 3B = 2 \Rightarrow 2 - 3B = 2 \Rightarrow -3B = 0 \Rightarrow B = 0$$
8. Step 6: Particular solution:
$$y_p = e^{-2x}(-x) = -x e^{-2x}$$
9. Final solution:
$$y = y_c + y_p = C_1 e^{-3x} + C_2 e^{x} - x e^{-2x}$$
Answer:
$$\boxed{y = C_1 e^{-3x} + C_2 e^{x} - x e^{-2x}}$$
Operator D Equation Ee33Ae
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.