Chapter 9: Problem 1
\(\mathbf{A}=\left[ \begin{array}{rr}{3} & {-2} \\ {0} & {3}\end{array}\right]\)
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Chapter 9: Problem 1
\(\mathbf{A}=\left[ \begin{array}{rr}{3} & {-2} \\ {0} & {3}\end{array}\right]\)
These are the key concepts you need to understand to accurately answer the question.
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\(\left| \begin{array}{rrr}{1} & {0} & {0} \\ {3} & {1} & {2} \\ {1} & {5} & {-2}\end{array}\right|\)
RLC-Network. The currents in the \(R L C\) network given by the schematic diagram in Figure 9.6 are governed by the following equations: $$ \begin{array}{l}{4 I_{2}^{\prime}(t)+52 q_{1}(t)=10} \\ {13 I_{3}(t)+52 q_{1}(t)=10} \\ {I_{1}(t)=I_{2}(t)+I_{3}(t)}\end{array} $$ where \(q_{1}(t)\) is the charge on the capacitor, \(I_{1}(t)=q_{1}^{\prime}(t)\) and initially \(q_{1}(0)=0\) coulombs and \(I_{1}(0)=0\) amps. Solve for the currents \(I_{1}, I_{2},\) and \(I_{3} .\) [Hint: Differentiate the first two equations, eliminate \(I_{1},\) and form a normal system with \(x_{1}=I_{2}, x_{2}=I_{2}^{\prime},\) and \(x_{3}=I_{3} . ]\)
In Problems \(31-34,\) solve the given initial value problem. \(\mathbf{x}^{\prime}(t)=\left[ \begin{array}{ll}{1} & {3} \\ {3} & {1}\end{array}\right] \mathbf{x}(t), \quad \mathbf{x}(0)=\left[ \begin{array}{l}{3} \\ {1}\end{array}\right]\)
37\. To illustrate the connection between a higher-order equation and the equivalent first-order system, consider the equation $$\quad y^{\prime \prime \prime}(t)-6 y^{\prime \prime}(t)+11 y^{\prime}(t)-6 y(t)=0.$$ (a) Show that \(\left\\{e^{t}, e^{2 t}, e^{3 t}\right\\}\) is a fundamental solution set for \((11)\) . (b) Using the definition in Section 6.1 , compute the Wronskian of \(\left(e^{t}, e^{2 t}, e^{3 t}\right)\) . (c) Setting \(x_{1}=y, x_{2}=y^{\prime}, x_{3}=y^{\prime \prime},\) show that equa- tion \((11)\) is equivalent to the first-order system $$(12) \quad \mathbf{x}^{\prime}=\mathbf{A} \mathbf{x}$$ where $$\mathbf{A} :=\left[ \begin{array}{rrr}{0} & {1} & {0} \\ {0} & {0} & {1} \\\ {6} & {-11} & {6}\end{array}\right].$$ (d) The substitution used in part (c) suggests that $$S :=\left\\{\left[ \begin{array}{c}{e^{t}} \\ {e^{t}} \\\ {e^{t}}\end{array}\right], \left[ \begin{array}{c}{e^{2 t}} \\ {2 e^{2 t}} \\\ {4 e^{2 t}}\end{array}\right], \left[ \begin{array}{c}{e^{3 t}} \\ {3 e^{3 t}} \\ {9 e^{3 t}}\end{array}\right]\right\\}$$ is a fundamental solution set for system \((12) .\) Verify that this is the case. (e) Compute the Wronskian of \(S .\) How does it compare with the Wronskian computed in part (b)?
$$ \mathbf{x}^{\prime}(t)=\left[ \begin{array}{rrr}{1} & {0} & {-1} \\ {0} & {2} & {0} \\ {1} & {0} & {1}\end{array}\right] \mathbf{x}(t) $$ $$ \quad \text { (a) }\ \mathbf{x}(0)=\left[ \begin{array}{r}{-2} \\ {2} \\ {-1}\end{array}\right] \quad \text { (b) } \quad \mathbf{x}(-\pi)=\left[ \begin{array}{l}{0} \\ {1} \\\ {1}\end{array}\right] $$
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