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<b>let </b><font color="Maroon">c1</font> be    <a href="ordinal1.html#NM1" target="_self">number</a> , <font color="Maroon">c2</font> be    <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>

<b>given </b><font color="Maroon">y1</font> being   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">y2</font> being   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">y3</font> being   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">y4</font> being   <a href="real_1.html#NM1">Real</a><b> such that </b><a NAME="E1:71_1_2"/><i><font color="Green">E40</font></i>: 
<font color="Maroon">y</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="quaterni.html#K6" target="_self">[*</a><span class="default"><font color="Maroon">y1</font>,<font color="Maroon">y2</font>,<font color="Maroon">y3</font>,<font color="Maroon">y4</font></span><a href="quaterni.html#K6" target="_self">*]</a></span>
 <b>and </b><br/><a NAME="E2:71_1_2"/><i><font color="Green">E41</font></i>: 
<font color="Maroon">c1</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="quaterni.html#K6" target="_self">[*</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon">x</font> <a href="real_1.html#K3">+</a> <font color="Maroon">y1</font></span>)</span>,<font color="Maroon">y2</font>,<font color="Maroon">y3</font>,<font color="Maroon">y4</font></span><a href="quaterni.html#K6" target="_self">*]</a></span>
 ;<br/>

<b>given </b><font color="Maroon">y1'</font> being   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">y2'</font> being   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">y3'</font> being   <a href="real_1.html#NM1">Real</a>, <font color="Maroon">y4'</font> being   <a href="real_1.html#NM1">Real</a><b> such that </b><a NAME="E3:71_1_2"/><i><font color="Green">E42</font></i>: 
<font color="Maroon">y</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="quaterni.html#K6" target="_self">[*</a><span class="default"><font color="Maroon">y1'</font>,<font color="Maroon">y2'</font>,<font color="Maroon">y3'</font>,<font color="Maroon">y4'</font></span><a href="quaterni.html#K6" target="_self">*]</a></span>
 <b>and </b><br/><a NAME="E4:71_1_2"/><i><font color="Green">E43</font></i>: 
<font color="Maroon">c2</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="quaterni.html#K6" target="_self">[*</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon">x</font> <a href="real_1.html#K3">+</a> <font color="Maroon">y1'</font></span>)</span>,<font color="Maroon">y2'</font>,<font color="Maroon">y3'</font>,<font color="Maroon">y4'</font></span><a href="quaterni.html#K6" target="_self">*]</a></span>
 ;<br/>

<a NAME="E5:71_1_2"/>
( <font color="Maroon">y1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y1'</font> &amp; <font color="Maroon">y2</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y2'</font> &amp; <font color="Maroon">y3</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y3'</font> &amp; <font color="Maroon">y4</font> <a href="hidden.html#R1">=</a> <font color="Maroon">y4'</font> )
 
<b>by </b><i><a class="txt" href="quaterni.html#E8"><i><font color="Green">Lemma45</font></i></a>, , </i>;<br/>
<b>hence </b><a NAME="E6:71_1_2"/>
<font color="Maroon">c1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">c2</font>
 <b>by </b><i>, </i>;<br/>


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