2. Solve the following differential equation, showing all work. Verify the solution you obtain. y" - 2y' + y = 0; y(0) = 1, y'(0) = -2.

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ISBN:9780470458365
Author:Erwin Kreyszig
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Chapter2: Second-order Linear Odes
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## Solving a Second-Order Differential Equation with Given Initial Conditions

2. **Problem Statement:**
   
   Solve the following differential equation, showing all work. Verify the solution you obtain.
   \[
   y'' - 2y' + y = 0; \quad y(0) = 1, \quad y'(0) = -2.
   \]

### Solution:

1. **Formulate the Characteristic Equation:**

   For the given differential equation:
   \[
   y'' - 2y' + y = 0,
   \]
   we find the characteristic equation by assuming \( y = e^{rt} \). Substituting \( y = e^{rt} \) into the differential equation, we get:
   \[
   r^2 e^{rt} - 2r e^{rt} + e^{rt} = 0.
   \]
   Factoring out \( e^{rt} \) (which is never zero), we get:
   \[
   r^2 - 2r + 1 = 0.
   \]

2. **Solve the Characteristic Equation:**

   Solve this quadratic equation:
   \[
   r^2 - 2r + 1 = 0.
   \]
   This simplifies to:
   \[
   (r - 1)^2 = 0,
   \]
   giving a repeated root:
   \[
   r = 1.
   \]

3. **Find the General Solution:**

   Since \( r = 1 \) is a repeated root, the general solution to the differential equation is:
   \[
   y(t) = (C_1 + C_2 t) e^{rt} = (C_1 + C_2 t) e^{t}.
   \]

4. **Apply the Initial Conditions:**

   Use the initial conditions to solve for the constants \( C_1 \) and \( C_2 \):
   
   \[
   y(0) = 1 \Rightarrow (C_1 + C_2 \cdot 0) e^0 = C_1 = 1.
   \]
   Thus, \( C_1 = 1 \).

   Next, differentiate the general solution to find \( y'(t) \):
   \[
   y'(t) = (C_1 + C_2 t
Transcribed Image Text:## Solving a Second-Order Differential Equation with Given Initial Conditions 2. **Problem Statement:** Solve the following differential equation, showing all work. Verify the solution you obtain. \[ y'' - 2y' + y = 0; \quad y(0) = 1, \quad y'(0) = -2. \] ### Solution: 1. **Formulate the Characteristic Equation:** For the given differential equation: \[ y'' - 2y' + y = 0, \] we find the characteristic equation by assuming \( y = e^{rt} \). Substituting \( y = e^{rt} \) into the differential equation, we get: \[ r^2 e^{rt} - 2r e^{rt} + e^{rt} = 0. \] Factoring out \( e^{rt} \) (which is never zero), we get: \[ r^2 - 2r + 1 = 0. \] 2. **Solve the Characteristic Equation:** Solve this quadratic equation: \[ r^2 - 2r + 1 = 0. \] This simplifies to: \[ (r - 1)^2 = 0, \] giving a repeated root: \[ r = 1. \] 3. **Find the General Solution:** Since \( r = 1 \) is a repeated root, the general solution to the differential equation is: \[ y(t) = (C_1 + C_2 t) e^{rt} = (C_1 + C_2 t) e^{t}. \] 4. **Apply the Initial Conditions:** Use the initial conditions to solve for the constants \( C_1 \) and \( C_2 \): \[ y(0) = 1 \Rightarrow (C_1 + C_2 \cdot 0) e^0 = C_1 = 1. \] Thus, \( C_1 = 1 \). Next, differentiate the general solution to find \( y'(t) \): \[ y'(t) = (C_1 + C_2 t
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