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Question:
BEEF :
SeEfEENL 285232
Este fii
i
HE RY Hi
i st H - Ha
i i == fe fr
Li i i:
i i = # i
H Hi = dre]
HEI Hi
= 1 : Hits
: ii HR
: £ kes
ES do
This is AI generated Response.
Asked by: Pradeep Rajora
Created at: 2025-10-03 04:05:46
Asked by: Pradeep Rajora
Created at: 2025-10-03 04:05:46
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Here’s a **structured breakdown** of the problem and step-by-step solution approach:
---
# Laplace Transform Differential Equation Problem
## **Given:**
A differential equation:
\[
\frac{d^2x}{dt^2} + 6\frac{dx}{dt} + 8x = 3u_1(t) + u_2(t)
\]
**Initial conditions:**
\(x() = 2\)
\(\frac{dx}{dt}() = 1\)
---
## **Instructions:**
### **a. Take Laplace Transform**
Apply the Laplace transform to both sides (using linearity and Laplace properties):
Let \( X(s) = \mathcal{L}\{ x(t) \} \)
\[
\mathcal{L}\left\{ \frac{d^2x}{dt^2} \right\} = s^2 X(s) - s x() - x'()
\]
\[
\mathcal{L}\left\{ \frac{dx}{dt} \right\} = s X(s) - x()
\]
\[
\mathcal{L}\{ x(t) \} = X(s)
\]
\[
\mathcal{L}\{ u_1(t) \} = \frac{1}{s}
\]
\[
\mathcal{L}\{ u_2(t) \} = \frac{1}{s}
\]
**Substitute values:**
\[
s^2 X(s) - s \cdot 2 - 1 + 6 (s X(s) - 2) + 8 X(s) = 3 \frac{1}{s} + \frac{1}{s}
\]
**Expand and collect terms:**
\[
s^2 X(s) - 2s - 1 + 6s X(s) - 12 + 8 X(s) = \frac{4}{s}
\]
Group \(X(s)\) terms:
\[
(s^2 + 6s + 8) X(s) - 2s - 1 - 12 = \frac{4}{s}
\]
\[
(s^2 + 6s + 8) X(s) - 2s - 13 = \frac{4}{s}
\]
\[
(s^2 + 6s + 8) X(s) = \frac{4}{s} + 2s + 13
\]
\[
X(s) = \frac{\frac{4}{s} + 2s + 13}{s^2 + 6s + 8}
\]
Or, combine:
\[
X(s) = \frac{4 + (2s + 13)s}{s(s^2 + 6s + 8)}
\]
\[
X(s) = \frac{2s^2 + 13s + 4}{s(s^2 + 6s + 8)}
\]
**Factored denominator:** \( s(s+4)(s+2) \)
So,
\[
X(s) = \frac{2s^2 + 13s + 4}{s(s+2)(s+4)}
\]
---
### **b. Predict the Final Value (Steady-State Output)**
Use the **Final Value Theorem**:
\[
\lim_{t \to \infty} x(t) = \lim_{s \to } s X(s)
\]
\[
\lim_{s \to } s \cdot \frac{2s^2 + 13s + 4}{s(s+2)(s+4)} = \lim_{s \to } \frac{2s^2 + 13s + 4}{(s+2)(s+4)}
\]
Substitute \(s = \):
\[
\frac{4}{8} = .5
\]
**Prediction:**
The final value of \(x(t)\) as \(t \to \infty\) is **.5**.
---
### **c. Inverse Laplace Transform (MATLAB)**
Use MATLAB to find the inverse Laplace:
```matlab
syms s t
X = (2*s^2 + 13*s + 4) / (s*(s+2)*(s+4));
x_t = ilaplace(X, s, t)
```
**Show MATLAB output and screenshot as required by your assignment.**
---
## **Summary Table**
| Step | Task | Formula/Command |
|------|-------------------------------------------|-------------------------------------------------------------|
| a | Laplace Transform | \( X(s) = \frac{2s^2 + 13s + 4}{s(s+2)(s+4)} \) |
| b | Final Value (Steady-State) | \( \lim_{s \to } s X(s) = .5 \) |
| c | Inverse Laplace (in MATLAB) | `ilaplace(X, s, t)` |
---
**Be sure to include a screenshot of your MATLAB workspace with your submission.**
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