<item ident="F5-2778" title="F5 | Substitution strategies | ver. 2778">
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<p>
<strong>F5.</strong>
</p>
<p> Apply each of the substitutions <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?u=\frac{y}{t}" alt="u=\frac{y}{t}" title="u=\frac{y}{t}" data-latex="u=\frac{y}{t}"/> and <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?u=at+by+c" alt="u=at+by+c" title="u=at+by+c" data-latex="u=at+by+c"/> to one of the following ODEs, and show that each result is separable. (Do not fully solve either ODE.) </p>
<ol type="a">
<li>
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?t y {y'} - 4 \, t^{2} + y^{2} = 0" alt="t y {y'} - 4 \, t^{2} + y^{2} = 0" title="t y {y'} - 4 \, t^{2} + y^{2} = 0" data-latex="t y {y'} - 4 \, t^{2} + y^{2} = 0"/>
</li>
<li>
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?y - \frac{4}{4 \, t - y + 5} - 9 = 4 \, t + {y'}" alt="y - \frac{4}{4 \, t - y + 5} - 9 = 4 \, t + {y'}" title="y - \frac{4}{4 \, t - y + 5} - 9 = 4 \, t + {y'}" data-latex="y - \frac{4}{4 \, t - y + 5} - 9 = 4 \, t + {y'}"/>
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<mattext texttype="text/html"><div class="exercise-statement">
<p>
<strong>F5.</strong>
</p>
<p> Apply each of the substitutions <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?u=%5Cfrac%7By%7D%7Bt%7D" alt="u=\frac{y}{t}" title="u=\frac{y}{t}" data-latex="u=\frac{y}{t}"> and <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?u=at+by+c" alt="u=at+by+c" title="u=at+by+c" data-latex="u=at+by+c"> to one of the following ODEs, and show that each result is separable. (Do not fully solve either ODE.) </p>
<ol type="a">
<li>
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?t%20y%20%7By'%7D%20-%204%20%5C,%20t%5E%7B2%7D%20+%20y%5E%7B2%7D%20=%200" alt="t y {y'} - 4 \, t^{2} + y^{2} = 0" title="t y {y'} - 4 \, t^{2} + y^{2} = 0" data-latex="t y {y'} - 4 \, t^{2} + y^{2} = 0">
</li>
<li>
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?y%20-%20%5Cfrac%7B4%7D%7B4%20%5C,%20t%20-%20y%20+%205%7D%20-%209%20=%204%20%5C,%20t%20+%20%7By'%7D" alt="y - \frac{4}{4 \, t - y + 5} - 9 = 4 \, t + {y'}" title="y - \frac{4}{4 \, t - y + 5} - 9 = 4 \, t + {y'}" data-latex="y - \frac{4}{4 \, t - y + 5} - 9 = 4 \, t + {y'}">
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<h4>Partial Answer:</h4>
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<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\frac{u {u'}}{u^{2} - 4} = \frac{1}{t}" alt="\frac{u {u'}}{u^{2} - 4} = \frac{1}{t}" title="\frac{u {u'}}{u^{2} - 4} = \frac{1}{t}" data-latex="\frac{u {u'}}{u^{2} - 4} = \frac{1}{t}"/>
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<li>
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\frac{u {u'}}{u^{2} + 4} = 1" alt="\frac{u {u'}}{u^{2} + 4} = 1" title="\frac{u {u'}}{u^{2} + 4} = 1" data-latex="\frac{u {u'}}{u^{2} + 4} = 1"/>
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<h4>Partial Answer:</h4>
<ol type="a">
<li>
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Cfrac%7Bu%20%7Bu'%7D%7D%7Bu%5E%7B2%7D%20-%204%7D%20=%20%5Cfrac%7B1%7D%7Bt%7D" alt="\frac{u {u'}}{u^{2} - 4} = \frac{1}{t}" title="\frac{u {u'}}{u^{2} - 4} = \frac{1}{t}" data-latex="\frac{u {u'}}{u^{2} - 4} = \frac{1}{t}">
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<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Cfrac%7Bu%20%7Bu'%7D%7D%7Bu%5E%7B2%7D%20+%204%7D%20=%201" alt="\frac{u {u'}}{u^{2} + 4} = 1" title="\frac{u {u'}}{u^{2} + 4} = 1" data-latex="\frac{u {u'}}{u^{2} + 4} = 1">
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