<item ident="S1-7357" title="S1 | Phase Planes | ver. 7357">
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<div class="exercise-statement">
<p>
<strong>S1.</strong>
</p>
<p> Draw a phase plane for the following system of ODEs. </p>
<p style="text-align:center;">
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?x'= 4 \, x + 4 \, y + 4" alt="x'= 4 \, x + 4 \, y + 4" title="x'= 4 \, x + 4 \, y + 4" data-latex="x'= 4 \, x + 4 \, y + 4"/>
</p>
<p style="text-align:center;">
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?y'= 4 \, x - 5 \, y + 13" alt="y'= 4 \, x - 5 \, y + 13" title="y'= 4 \, x - 5 \, y + 13" data-latex="y'= 4 \, x - 5 \, y + 13"/>
</p>
<p>Be sure to include and label the following features in your sketch:</p>
<ul>
<li>The isoclines <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?x'=0" alt="x'=0" title="x'=0" data-latex="x'=0"/> and <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?y'=0" alt="y'=0" title="y'=0" data-latex="y'=0"/>.</li>
<li>Arrow systems describing trajectories of solutions.</li>
<li>The equillibrium of the system.</li>
</ul>
</div>
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<mattext texttype="text/html"><div class="exercise-statement">
<p>
<strong>S1.</strong>
</p>
<p> Draw a phase plane for the following system of ODEs. </p>
<p style="text-align:center;">
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?x'=%204%20%5C,%20x%20+%204%20%5C,%20y%20+%204" alt="x'= 4 \, x + 4 \, y + 4" title="x'= 4 \, x + 4 \, y + 4" data-latex="x'= 4 \, x + 4 \, y + 4">
</p>
<p style="text-align:center;">
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?y'=%204%20%5C,%20x%20-%205%20%5C,%20y%20+%2013" alt="y'= 4 \, x - 5 \, y + 13" title="y'= 4 \, x - 5 \, y + 13" data-latex="y'= 4 \, x - 5 \, y + 13">
</p>
<p>Be sure to include and label the following features in your sketch:</p>
<ul>
<li>The isoclines <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?x'=0" alt="x'=0" title="x'=0" data-latex="x'=0"> and <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?y'=0" alt="y'=0" title="y'=0" data-latex="y'=0">.</li>
<li>Arrow systems describing trajectories of solutions.</li>
<li>The equillibrium of the system.</li>
</ul>
</div>
</mattext>
</material>
<response_str ident="response1" rcardinality="Single">
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<response_label ident="answer1" rshuffle="No"/>
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<div class="exercise-answer">
<h4>Partial Answer:</h4>
<p> The isoclines cross at the equillibrium <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\left(-2, 1\right)" alt="\left(-2, 1\right)" title="\left(-2, 1\right)" data-latex="\left(-2, 1\right)"/>, with <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?x'=0" alt="x'=0" title="x'=0" data-latex="x'=0"/> having a negative slope and <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?y'=0" alt="y'=0" title="y'=0" data-latex="y'=0"/> having a positive slope. </p>
<p> The right region has a northeast arrow system, the top region has a southeast arrow system, the left region has a southwest arrow system, and the bottom region has a northwest arrow system. </p>
</div>
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<mattext texttype="text/html"><div class="exercise-answer">
<h4>Partial Answer:</h4>
<p> The isoclines cross at the equillibrium <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Cleft(-2,%201%5Cright)" alt="\left(-2, 1\right)" title="\left(-2, 1\right)" data-latex="\left(-2, 1\right)">, with <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?x'=0" alt="x'=0" title="x'=0" data-latex="x'=0"> having a negative slope and <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?y'=0" alt="y'=0" title="y'=0" data-latex="y'=0"> having a positive slope. </p>
<p> The right region has a northeast arrow system, the top region has a southeast arrow system, the left region has a southwest arrow system, and the bottom region has a northwest arrow system. </p>
</div>
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