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QuestionMathematics

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Step 1:
: Graph the forcing function, $f(t)$

Graph of $f(t)$:
f(t) = \begin{cases} 1 & \text{if } t \geq \pi, \ 0 & \text{if } t < \pi. \end{cases} t / f(t) --------- 0 / 0 \ pi / 1 \ 3pi / 1

Step 2:
: Find the Laplace transform of the differential equation

Taking the Laplace transform of both sides, we get: \mathcal{L}\{\bar{y}+ 4\dot{y}+ 5y\} = \mathcal{L}\{f(t)\} Using linearity property and known Laplace transforms, we have: \mathcal{L}\{\bar{y}\} + 4\mathcal{L}\{\dot{y}\} + 5\mathcal{L}\{y\} = \mathcal{L}\{1\} - \mathcal{L}\{u(t-\pi)\}

Step 3:
: Apply initial conditions

where $Y(s)$ is the Laplace transform of $y(t)$.
Using these initial conditions, we can find the Laplace transforms: \begin{align*} \mathcal{L}\{\bar{y}\} &= sY(s) - y(0) = sY(s), \ \mathcal{L}\{\dot{y}\} &= sY(s) - y(0) = sY(s), \end{align*}

Step 4:
: Solve for $Y(s)$

Substituting the Laplace transforms from Step 3 into the equation from Step 2, we get: Simplifying, we have:

Step 5:
: Partial fraction decomposition

The first term can be decomposed as: So,

Step 6:
: Inverse Laplace transform

\begin{align*} \end{align*}

Step 7:
: Simplified expressions for $y(t)$

y(2$) = 1 - u(2$)

Step 8:
: Sketch the graph of the solution

The graph of the solution is a step function that increases by $\frac{1}{9}$ at $t = \pi$.
t / y(2$) --------- 0 / 0 \ pi / 0 \ 3pi / 1 / 9

Final Answer

- Simplified expressions for $y(t)$: see Step 7 - Sketch of the graph: see Step 8