<item ident="A3-0000" title="A3 | Image and kernel | ver. 0000"> <itemmetadata> <qtimetadata> <qtimetadatafield> <fieldlabel>question_type</fieldlabel> <fieldentry>essay_question</fieldentry> </qtimetadatafield> </qtimetadata> </itemmetadata> <presentation> <material> <mattextxml> <div class="exercise-statement"><p><strong>A3.</strong></p> Let <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T:\mathbb{R}^ 3 \to \mathbb{R}^ 4" alt="T:\mathbb{R}^ 3 \to \mathbb{R}^ 4" title="T:\mathbb{R}^ 3 \to \mathbb{R}^ 4" data-latex="T:\mathbb{R}^ 3 \to \mathbb{R}^ 4"/> be the linear transformation given by <p style="text-align:center;"><img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T\left( \left[\begin{array}{c} x \\ y \\ z \end{array}\right] \right) = \left[\begin{array}{c} x + 3 \, y - z \\ -3 \, x - 8 \, y + 2 \, z \\ -4 \, x - 8 \, y \\ -x - 7 \, y + 5 \, z \end{array}\right] ." alt="T\left( \left[\begin{array}{c} x \\ y \\ z \end{array}\right] \right) = \left[\begin{array}{c} x + 3 \, y - z \\ -3 \, x - 8 \, y + 2 \, z \\ -4 \, x - 8 \, y \\ -x - 7 \, y + 5 \, z \end{array}\right] ." title="T\left( \left[\begin{array}{c} x \\ y \\ z \end{array}\right] \right) = \left[\begin{array}{c} x + 3 \, y - z \\ -3 \, x - 8 \, y + 2 \, z \\ -4 \, x - 8 \, y \\ -x - 7 \, y + 5 \, z \end{array}\right] ." data-latex="T\left( \left[\begin{array}{c} x \\ y \\ z \end{array}\right] \right) = \left[\begin{array}{c} x + 3 \, y - z \\ -3 \, x - 8 \, y + 2 \, z \\ -4 \, x - 8 \, y \\ -x - 7 \, y + 5 \, z \end{array}\right] ."/></p><ol type="a"><li>Explain how to find the image of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/> and the kernel of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/>.</li><li>Explain how to find a basis of the image of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/> and a basis of the kernel of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/>.</li><li>Explain how to find the rank and nullity of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/>, and why the rank-nullity theorem holds for <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/>.</li></ol></div> </mattextxml> <mattext texttype="text/html"><div class="exercise-statement"> <p><strong>A3.</strong></p> Let <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T:%5Cmathbb%7BR%7D%5E%203%20%5Cto%20%5Cmathbb%7BR%7D%5E%204" alt="T:\mathbb{R}^ 3 \to \mathbb{R}^ 4" title="T:\mathbb{R}^ 3 \to \mathbb{R}^ 4" data-latex="T:\mathbb{R}^ 3 \to \mathbb{R}^ 4"> be the linear transformation given by <p style="text-align:center;"><img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T%5Cleft(%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D%20x%20%5C%5C%20y%20%5C%5C%20z%20%5Cend%7Barray%7D%5Cright%5D%20%5Cright)%20=%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D%20x%20+%203%20%5C,%20y%20-%20z%20%5C%5C%20-3%20%5C,%20x%20-%208%20%5C,%20y%20+%202%20%5C,%20z%20%5C%5C%20-4%20%5C,%20x%20-%208%20%5C,%20y%20%5C%5C%20-x%20-%207%20%5C,%20y%20+%205%20%5C,%20z%20%5Cend%7Barray%7D%5Cright%5D%20." alt="T\left( \left[\begin{array}{c} x \\ y \\ z \end{array}\right] \right) = \left[\begin{array}{c} x + 3 \, y - z \\ -3 \, x - 8 \, y + 2 \, z \\ -4 \, x - 8 \, y \\ -x - 7 \, y + 5 \, z \end{array}\right] ." title="T\left( \left[\begin{array}{c} x \\ y \\ z \end{array}\right] \right) = \left[\begin{array}{c} x + 3 \, y - z \\ -3 \, x - 8 \, y + 2 \, z \\ -4 \, x - 8 \, y \\ -x - 7 \, y + 5 \, z \end{array}\right] ." data-latex="T\left( \left[\begin{array}{c} x \\ y \\ z \end{array}\right] \right) = \left[\begin{array}{c} x + 3 \, y - z \\ -3 \, x - 8 \, y + 2 \, z \\ -4 \, x - 8 \, y \\ -x - 7 \, y + 5 \, z \end{array}\right] ."></p> <ol type="a"> <li>Explain how to find the image of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"> and the kernel of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T">.</li> <li>Explain how to find a basis of the image of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"> and a basis of the kernel of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T">.</li> <li>Explain how to find the rank and nullity of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T">, and why the rank-nullity theorem holds for <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T">.</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> <p> <p style="text-align:center;"> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\operatorname{RREF} \left[\begin{array}{ccc} 1 & 3 & -1 \\ -3 & -8 & 2 \\ -4 & -8 & 0 \\ -1 & -7 & 5 \end{array}\right] = \left[\begin{array}{ccc} 1 & 0 & 2 \\ 0 & 1 & -1 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{array}\right]" alt="\operatorname{RREF} \left[\begin{array}{ccc} 1 & 3 & -1 \\ -3 & -8 & 2 \\ -4 & -8 & 0 \\ -1 & -7 & 5 \end{array}\right] = \left[\begin{array}{ccc} 1 & 0 & 2 \\ 0 & 1 & -1 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{array}\right]" title="\operatorname{RREF} \left[\begin{array}{ccc} 1 & 3 & -1 \\ -3 & -8 & 2 \\ -4 & -8 & 0 \\ -1 & -7 & 5 \end{array}\right] = \left[\begin{array}{ccc} 1 & 0 & 2 \\ 0 & 1 & -1 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{array}\right]" data-latex="\operatorname{RREF} \left[\begin{array}{ccc} 1 & 3 & -1 \\ -3 & -8 & 2 \\ -4 & -8 & 0 \\ -1 & -7 & 5 \end{array}\right] = \left[\begin{array}{ccc} 1 & 0 & 2 \\ 0 & 1 & -1 \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{array}\right]"/> </p> </p> <ol type="a"> <li> <p style="text-align:center;"> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\operatorname{Im}\ T = \operatorname{span}\ \left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" alt="\operatorname{Im}\ T = \operatorname{span}\ \left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" title="\operatorname{Im}\ T = \operatorname{span}\ \left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" data-latex="\operatorname{Im}\ T = \operatorname{span}\ \left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}"/> </p> <p style="text-align:center;"> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\operatorname{ker}\ T = \left\{ \left[\begin{array}{c} -2 \, a \\ a \\ a \end{array}\right] \middle|\,a\in\mathbb{R}\right\}" alt="\operatorname{ker}\ T = \left\{ \left[\begin{array}{c} -2 \, a \\ a \\ a \end{array}\right] \middle|\,a\in\mathbb{R}\right\}" title="\operatorname{ker}\ T = \left\{ \left[\begin{array}{c} -2 \, a \\ a \\ a \end{array}\right] \middle|\,a\in\mathbb{R}\right\}" data-latex="\operatorname{ker}\ T = \left\{ \left[\begin{array}{c} -2 \, a \\ a \\ a \end{array}\right] \middle|\,a\in\mathbb{R}\right\}"/> </p> </li> <li> A basis of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\operatorname{Im}\ T" alt="\operatorname{Im}\ T" title="\operatorname{Im}\ T" data-latex="\operatorname{Im}\ T"/> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" alt="\left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" title="\left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" data-latex="\left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}"/>. A basis of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\operatorname{ker}\ T" alt="\operatorname{ker}\ T" title="\operatorname{ker}\ T" data-latex="\operatorname{ker}\ T"/> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\left\{ \left[\begin{array}{c} -2 \\ 1 \\ 1 \end{array}\right] \right\}" alt="\left\{ \left[\begin{array}{c} -2 \\ 1 \\ 1 \end{array}\right] \right\}" title="\left\{ \left[\begin{array}{c} -2 \\ 1 \\ 1 \end{array}\right] \right\}" data-latex="\left\{ \left[\begin{array}{c} -2 \\ 1 \\ 1 \end{array}\right] \right\}"/></li> <li> The rank of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?2" alt="2" title="2" data-latex="2"/>, the nullity of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?1" alt="1" title="1" data-latex="1"/>, and the dimension of the domain of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"/> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?3" alt="3" title="3" data-latex="3"/>. The rank-nullity theorem asserts that <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?2 + 1 = 3" alt="2 + 1 = 3" title="2 + 1 = 3" data-latex="2 + 1 = 3"/>, which we see to be true. </li> </ol> </div> </mattextxml> <mattext texttype="text/html"><div class="exercise-answer"> <h4>Partial Answer:</h4> <p> </p> <p style="text-align:center;"> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Coperatorname%7BRREF%7D%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D%201%20&amp;%203%20&amp;%20-1%20%5C%5C%20-3%20&amp;%20-8%20&amp;%202%20%5C%5C%20-4%20&amp;%20-8%20&amp;%200%20%5C%5C%20-1%20&amp;%20-7%20&amp;%205%20%5Cend%7Barray%7D%5Cright%5D%20=%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D%201%20&amp;%200%20&amp;%202%20%5C%5C%200%20&amp;%201%20&amp;%20-1%20%5C%5C%200%20&amp;%200%20&amp;%200%20%5C%5C%200%20&amp;%200%20&amp;%200%20%5Cend%7Barray%7D%5Cright%5D" alt="\operatorname{RREF} \left[\begin{array}{ccc} 1 &amp; 3 &amp; -1 \\ -3 &amp; -8 &amp; 2 \\ -4 &amp; -8 &amp; 0 \\ -1 &amp; -7 &amp; 5 \end{array}\right] = \left[\begin{array}{ccc} 1 &amp; 0 &amp; 2 \\ 0 &amp; 1 &amp; -1 \\ 0 &amp; 0 &amp; 0 \\ 0 &amp; 0 &amp; 0 \end{array}\right]" title="\operatorname{RREF} \left[\begin{array}{ccc} 1 &amp; 3 &amp; -1 \\ -3 &amp; -8 &amp; 2 \\ -4 &amp; -8 &amp; 0 \\ -1 &amp; -7 &amp; 5 \end{array}\right] = \left[\begin{array}{ccc} 1 &amp; 0 &amp; 2 \\ 0 &amp; 1 &amp; -1 \\ 0 &amp; 0 &amp; 0 \\ 0 &amp; 0 &amp; 0 \end{array}\right]" data-latex="\operatorname{RREF} \left[\begin{array}{ccc} 1 &amp; 3 &amp; -1 \\ -3 &amp; -8 &amp; 2 \\ -4 &amp; -8 &amp; 0 \\ -1 &amp; -7 &amp; 5 \end{array}\right] = \left[\begin{array}{ccc} 1 &amp; 0 &amp; 2 \\ 0 &amp; 1 &amp; -1 \\ 0 &amp; 0 &amp; 0 \\ 0 &amp; 0 &amp; 0 \end{array}\right]"> </p> <ol type="a"> <li> <p style="text-align:center;"> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Coperatorname%7BIm%7D%5C%20T%20=%20%5Coperatorname%7Bspan%7D%5C%20%5Cleft%5C%7B%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D%201%20%5C%5C%20-3%20%5C%5C%20-4%20%5C%5C%20-1%20%5Cend%7Barray%7D%5Cright%5D%20,%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D%203%20%5C%5C%20-8%20%5C%5C%20-8%20%5C%5C%20-7%20%5Cend%7Barray%7D%5Cright%5D%20%5Cright%5C%7D" alt="\operatorname{Im}\ T = \operatorname{span}\ \left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" title="\operatorname{Im}\ T = \operatorname{span}\ \left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" data-latex="\operatorname{Im}\ T = \operatorname{span}\ \left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}"> </p> <p style="text-align:center;"> <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Coperatorname%7Bker%7D%5C%20T%20=%20%5Cleft%5C%7B%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D%20-2%20%5C,%20a%20%5C%5C%20a%20%5C%5C%20a%20%5Cend%7Barray%7D%5Cright%5D%20%5Cmiddle%7C%5C,a%5Cin%5Cmathbb%7BR%7D%5Cright%5C%7D" alt="\operatorname{ker}\ T = \left\{ \left[\begin{array}{c} -2 \, a \\ a \\ a \end{array}\right] \middle|\,a\in\mathbb{R}\right\}" title="\operatorname{ker}\ T = \left\{ \left[\begin{array}{c} -2 \, a \\ a \\ a \end{array}\right] \middle|\,a\in\mathbb{R}\right\}" data-latex="\operatorname{ker}\ T = \left\{ \left[\begin{array}{c} -2 \, a \\ a \\ a \end{array}\right] \middle|\,a\in\mathbb{R}\right\}"> </p> </li> <li> A basis of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Coperatorname%7BIm%7D%5C%20T" alt="\operatorname{Im}\ T" title="\operatorname{Im}\ T" data-latex="\operatorname{Im}\ T"> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Cleft%5C%7B%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D%201%20%5C%5C%20-3%20%5C%5C%20-4%20%5C%5C%20-1%20%5Cend%7Barray%7D%5Cright%5D%20,%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D%203%20%5C%5C%20-8%20%5C%5C%20-8%20%5C%5C%20-7%20%5Cend%7Barray%7D%5Cright%5D%20%5Cright%5C%7D" alt="\left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" title="\left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}" data-latex="\left\{ \left[\begin{array}{c} 1 \\ -3 \\ -4 \\ -1 \end{array}\right] , \left[\begin{array}{c} 3 \\ -8 \\ -8 \\ -7 \end{array}\right] \right\}">. A basis of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Coperatorname%7Bker%7D%5C%20T" alt="\operatorname{ker}\ T" title="\operatorname{ker}\ T" data-latex="\operatorname{ker}\ T"> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Cleft%5C%7B%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D%20-2%20%5C%5C%201%20%5C%5C%201%20%5Cend%7Barray%7D%5Cright%5D%20%5Cright%5C%7D" alt="\left\{ \left[\begin{array}{c} -2 \\ 1 \\ 1 \end{array}\right] \right\}" title="\left\{ \left[\begin{array}{c} -2 \\ 1 \\ 1 \end{array}\right] \right\}" data-latex="\left\{ \left[\begin{array}{c} -2 \\ 1 \\ 1 \end{array}\right] \right\}"> </li> <li> The rank of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?2" alt="2" title="2" data-latex="2">, the nullity of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?1" alt="1" title="1" data-latex="1">, and the dimension of the domain of <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?T" alt="T" title="T" data-latex="T"> is <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?3" alt="3" title="3" data-latex="3">. The rank-nullity theorem asserts that <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?2%20+%201%20=%203" alt="2 + 1 = 3" title="2 + 1 = 3" data-latex="2 + 1 = 3">, which we see to be true. </li> </ol> </div> </mattext> </material> </flow_mat> </itemfeedback> </item>