<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon" title="c7">c1</font>, <font color="Maroon" title="c8">c2</font> be    <a href="ordinal1.html#NM1" title="ORDINAL1:NM.1">number</a> ;<br/>

<b>given </b><font color="Maroon" title="c9">y1</font>, <font color="Maroon" title="c10">y2</font>, <font color="Maroon" title="c11">y3</font>, <font color="Maroon" title="c12">y4</font> being   <a href="real_1.html#NM1" title="REAL_1:NM.1">Real</a><b> such that </b><a NAME="E2:71_1_2"/><i><font color="Green" title="E45">A2</font></i>: 
<font color="Maroon" title="c2">y</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1"><a href="quaterni.html#K6" title="QUATERNI:func.6">[*</a><span class="default"><font color="Maroon" title="c9">y1</font>,<font color="Maroon" title="c10">y2</font>,<font color="Maroon" title="c11">y3</font>,<font color="Maroon" title="c12">y4</font></span><a href="quaterni.html#K6" title="QUATERNI:func.6">*]</a></span>
 <b>and </b><br/><a NAME="E3:71_1_2"/><i><font color="Green" title="E46">A3</font></i>: 
<font color="Maroon" title="c7">c1</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1"><a href="quaterni.html#K6" title="QUATERNI:func.6">[*</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c1">x</font> <a href="real_1.html#K7" title="REAL_1:func.7">+</a> <font color="Maroon" title="c9">y1</font></span>)</span>,<font color="Maroon" title="c10">y2</font>,<font color="Maroon" title="c11">y3</font>,<font color="Maroon" title="c12">y4</font></span><a href="quaterni.html#K6" title="QUATERNI:func.6">*]</a></span>
 ;<br/>

<b>given </b><font color="Maroon" title="c13">y1'</font>, <font color="Maroon" title="c14">y2'</font>, <font color="Maroon" title="c15">y3'</font>, <font color="Maroon" title="c16">y4'</font> being   <a href="real_1.html#NM1" title="REAL_1:NM.1">Real</a><b> such that </b><a NAME="E5:71_1_2"/><i><font color="Green" title="E47">A4</font></i>: 
<font color="Maroon" title="c2">y</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1"><a href="quaterni.html#K6" title="QUATERNI:func.6">[*</a><span class="default"><font color="Maroon" title="c13">y1'</font>,<font color="Maroon" title="c14">y2'</font>,<font color="Maroon" title="c15">y3'</font>,<font color="Maroon" title="c16">y4'</font></span><a href="quaterni.html#K6" title="QUATERNI:func.6">*]</a></span>
 <b>and </b><br/><a NAME="E6:71_1_2"/><i><font color="Green" title="E48">A5</font></i>: 
<font color="Maroon" title="c8">c2</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <span class="p1"><a href="quaterni.html#K6" title="QUATERNI:func.6">[*</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c1">x</font> <a href="real_1.html#K7" title="REAL_1:func.7">+</a> <font color="Maroon" title="c13">y1'</font></span>)</span>,<font color="Maroon" title="c14">y2'</font>,<font color="Maroon" title="c15">y3'</font>,<font color="Maroon" title="c16">y4'</font></span><a href="quaterni.html#K6" title="QUATERNI:func.6">*]</a></span>
 ;<br/>

<a NAME="E7:71_1_2"/>
( <font color="Maroon" title="c9">y1</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c13">y1'</font> &amp; <font color="Maroon" title="c10">y2</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c14">y2'</font> &amp; <font color="Maroon" title="c11">y3</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c15">y3'</font> &amp; <font color="Maroon" title="c12">y4</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c16">y4'</font> )
 
<b>by </b><i><a class="txt" href="quaterni.html#E2:71_1_2"><i><font color="Green" title="E45">A2</font></i></a>, <a class="txt" href="quaterni.html#E5:71_1_2"><i><font color="Green" title="E47">A4</font></i></a>, <a class="ref" href="quaterni.html#T12" target="_self" title="QUATERNI:th.12">Th12</a></i>;<br/>
<b>hence </b><a NAME="E8:71_1_2"/>
<font color="Maroon" title="c7">c1</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c8">c2</font>
 <b>by </b><i><a class="txt" href="quaterni.html#E3:71_1_2"><i><font color="Green" title="E46">A3</font></i></a>, <a class="txt" href="quaterni.html#E6:71_1_2"><i><font color="Green" title="E48">A5</font></i></a></i>;<br/>


</div>
