<item ident="F5-6868" title="F5 | Substitution strategies | ver. 6868"> <itemmetadata> <qtimetadata> <qtimetadatafield> <fieldlabel>question_type</fieldlabel> <fieldentry>essay_question</fieldentry> </qtimetadatafield> </qtimetadata> </itemmetadata> <presentation> <material> <mattextxml> <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=\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?-5 \, t^{2} = t y {y'} + y^{2}" alt="-5 \, t^{2} = t y {y'} + y^{2}" title="-5 \, t^{2} = t y {y'} + y^{2}" data-latex="-5 \, t^{2} = t y {y'} + y^{2}"/> </li> <li> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?-2 \, t - {y'} = -y - \frac{3}{2 \, t - y - 2}" alt="-2 \, t - {y'} = -y - \frac{3}{2 \, t - y - 2}" title="-2 \, t - {y'} = -y - \frac{3}{2 \, t - y - 2}" data-latex="-2 \, t - {y'} = -y - \frac{3}{2 \, t - y - 2}"/> </li> </ol> </div> </mattextxml> <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?-5%20%5C,%20t%5E%7B2%7D%20=%20t%20y%20%7By'%7D%20+%20y%5E%7B2%7D" alt="-5 \, t^{2} = t y {y'} + y^{2}" title="-5 \, t^{2} = t y {y'} + y^{2}" data-latex="-5 \, t^{2} = t y {y'} + y^{2}"> </li> <li> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?-2%20%5C,%20t%20-%20%7By'%7D%20=%20-y%20-%20%5Cfrac%7B3%7D%7B2%20%5C,%20t%20-%20y%20-%202%7D" alt="-2 \, t - {y'} = -y - \frac{3}{2 \, t - y - 2}" title="-2 \, t - {y'} = -y - \frac{3}{2 \, t - y - 2}" data-latex="-2 \, t - {y'} = -y - \frac{3}{2 \, t - y - 2}"> </li> </ol> </div> </mattext> </material> <response_str ident="response1" rcardinality="Single"> <render_fib> <response_label ident="answer1" rshuffle="No"/> </render_fib> </response_str> </presentation> <itemfeedback ident="general_fb"> <flow_mat> <material> <mattextxml> <div class="exercise-answer"> <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?\frac{u {u'}}{u^{2} + 5} = \frac{1}{t}" alt="\frac{u {u'}}{u^{2} + 5} = \frac{1}{t}" title="\frac{u {u'}}{u^{2} + 5} = \frac{1}{t}" data-latex="\frac{u {u'}}{u^{2} + 5} = \frac{1}{t}"/> </li> <li> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\frac{u {u'}}{u^{2} - 3} = 1" alt="\frac{u {u'}}{u^{2} - 3} = 1" title="\frac{u {u'}}{u^{2} - 3} = 1" data-latex="\frac{u {u'}}{u^{2} - 3} = 1"/> </li> </ol> </div> </mattextxml> <mattext texttype="text/html"><div class="exercise-answer"> <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+%205%7D%20=%20%5Cfrac%7B1%7D%7Bt%7D" alt="\frac{u {u'}}{u^{2} + 5} = \frac{1}{t}" title="\frac{u {u'}}{u^{2} + 5} = \frac{1}{t}" data-latex="\frac{u {u'}}{u^{2} + 5} = \frac{1}{t}"> </li> <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-%203%7D%20=%201" alt="\frac{u {u'}}{u^{2} - 3} = 1" title="\frac{u {u'}}{u^{2} - 3} = 1" data-latex="\frac{u {u'}}{u^{2} - 3} = 1"> </li> </ol> </div> </mattext> </material> </flow_mat> </itemfeedback> </item>