<item ident="V1-0005" title="V1 | Vector spaces | ver. 0005">
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<p>
<strong>V1.</strong>
</p>
<p> Let <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?V" alt="V" title="V" data-latex="V"/> be the set of all pairs <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?(x,y)" alt="(x,y)" title="(x,y)" data-latex="(x,y)"/> of real numbers together with the following operations: </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_1,y_1)\oplus (x_2,y_2)= \left(x_{1} x_{2},\,y_{1} y_{2}\right)" alt="(x_1,y_1)\oplus (x_2,y_2)= \left(x_{1} x_{2},\,y_{1} y_{2}\right)" title="(x_1,y_1)\oplus (x_2,y_2)= \left(x_{1} x_{2},\,y_{1} y_{2}\right)" data-latex="(x_1,y_1)\oplus (x_2,y_2)= \left(x_{1} x_{2},\,y_{1} y_{2}\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?c \odot (x,y) = \left(x^{c},\,y^{c}\right) ." alt="c \odot (x,y) = \left(x^{c},\,y^{c}\right) ." title="c \odot (x,y) = \left(x^{c},\,y^{c}\right) ." data-latex="c \odot (x,y) = \left(x^{c},\,y^{c}\right) ."/>
</p>
<p> (a) Show that there exists an additive identity element, that is: </p>
<p style="text-align:center;">
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?\text{There exists }(w,z)\in V\text{ such that }(x,y)\oplus(w,z)=(x,y)." alt="\text{There exists }(w,z)\in V\text{ such that }(x,y)\oplus(w,z)=(x,y)." title="\text{There exists }(w,z)\in V\text{ such that }(x,y)\oplus(w,z)=(x,y)." data-latex="\text{There exists }(w,z)\in V\text{ such that }(x,y)\oplus(w,z)=(x,y)."/>
</p>
<p> (b) Explain why <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?V" alt="V" title="V" data-latex="V"/> nonetheless is not a vector space. </p>
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<mattext texttype="text/html"><div class="exercise-statement">
<p>
<strong>V1.</strong>
</p>
<p> Let <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?V" alt="V" title="V" data-latex="V"> be the set of all pairs <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?(x,y)" alt="(x,y)" title="(x,y)" data-latex="(x,y)"> of real numbers together with the following operations: </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_1,y_1)%5Coplus%20(x_2,y_2)=%20%5Cleft(x_%7B1%7D%20x_%7B2%7D,%5C,y_%7B1%7D%20y_%7B2%7D%5Cright)" alt="(x_1,y_1)\oplus (x_2,y_2)= \left(x_{1} x_{2},\,y_{1} y_{2}\right)" title="(x_1,y_1)\oplus (x_2,y_2)= \left(x_{1} x_{2},\,y_{1} y_{2}\right)" data-latex="(x_1,y_1)\oplus (x_2,y_2)= \left(x_{1} x_{2},\,y_{1} y_{2}\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?c%20%5Codot%20(x,y)%20=%20%5Cleft(x%5E%7Bc%7D,%5C,y%5E%7Bc%7D%5Cright)%20." alt="c \odot (x,y) = \left(x^{c},\,y^{c}\right) ." title="c \odot (x,y) = \left(x^{c},\,y^{c}\right) ." data-latex="c \odot (x,y) = \left(x^{c},\,y^{c}\right) .">
</p>
<p> (a) Show that there exists an additive identity element, that is: </p>
<p style="text-align:center;">
<img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?%5Ctext%7BThere%20exists%20%7D(w,z)%5Cin%20V%5Ctext%7B%20such%20that%20%7D(x,y)%5Coplus(w,z)=(x,y)." alt="\text{There exists }(w,z)\in V\text{ such that }(x,y)\oplus(w,z)=(x,y)." title="\text{There exists }(w,z)\in V\text{ such that }(x,y)\oplus(w,z)=(x,y)." data-latex="\text{There exists }(w,z)\in V\text{ such that }(x,y)\oplus(w,z)=(x,y).">
</p>
<p> (b) Explain why <img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?V" alt="V" title="V" data-latex="V"> nonetheless is not a vector space. </p>
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<h4>Partial Answer:</h4>
<p><img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?V" alt="V" title="V" data-latex="V"/> is not a vector space, which may be shown by demonstrating that any one of the following properties do not hold: </p>
<ul>
<li>additive inverses do not always exist</li>
</ul>
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<mattext texttype="text/html"><div class="exercise-answer">
<h4>Partial Answer:</h4>
<p><img style="border:1px #ddd solid;padding:5px;border-radius:5px;" src="https://latex.codecogs.com/svg.latex?V" alt="V" title="V" data-latex="V"> is not a vector space, which may be shown by demonstrating that any one of the following properties do not hold: </p>
<ul>
<li>additive inverses do not always exist</li>
</ul>
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