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<b>let </b><font color="Maroon">r</font> be  <a href="xreal_0.html#V1" target="_self">real</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/><b>let </b><font color="Maroon">s</font> be  <a href="xreal_0.html#V1" target="_self">real</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>



<b>assume </b><a NAME="E1:16"/><i><font color="Green">E20</font></i>: 
<font color="Maroon">r</font> <a href="xcmplx_0.html#K3">*</a> <font color="Maroon">s</font> <a href="hidden.html#R1">=</a> 0
 ;<br/>

<b>assume </b><a NAME="E2:16"/><i><font color="Green">E21</font></i>: 
<font color="Maroon">r</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0
 ;<br/>

<a NAME="E3:16"/>
<span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">r</font> <a href="xcmplx_0.html#K5">"</a> </span>)</span> <a href="xcmplx_0.html#K3">*</a> <font color="Maroon">r</font></span>)</span> <a href="xcmplx_0.html#K3">*</a> <font color="Maroon">s</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">r</font> <a href="xcmplx_0.html#K5">"</a> </span>)</span> <a href="xcmplx_0.html#K3">*</a> 0
 
<b>by </b><i>, <a class="txt" href="xreal_0.html#E2:16"><i><font color="Green">E21</font></i></a></i>;<br/>
<a NAME="E4:16"/><b>then </b>
1 <a href="xcmplx_0.html#K3">*</a> <font color="Maroon">s</font> <a href="hidden.html#R1">=</a> 0
 
<b>by </b><i><a class="txt" href="xreal_0.html#E2"><i><font color="Green">Lemma24</font></i></a>, <a class="ref" href="xcmplx_0.html#D7">XCMPLX_0:def 7</a></i>;<br/>
<b>hence </b><a NAME="E5:16"/>
<font color="Maroon">s</font> <a href="hidden.html#R1">=</a> 0
 ;<br/>


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