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<a NAME="E1:27_1_1"/><i><font color="Green">E28</font></i>: 
 <a href="xcmplx_0.html#K4">-</a> <span class="p1">(<span class="default"><a href="xcmplx_0.html#K4">-</a> <font color="Maroon">c<sub>8</sub></font></span>)</span> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a> 0
 
<b>by </b><i><a class="ref" href="xxreal_0.html#D7">XXREAL_0:def 7</a></i>;<br/>
<b>assume </b><a NAME="E2:27_1_1"/>
 <a href="xcmplx_0.html#K4">-</a> <font color="Maroon">c<sub>8</sub></font> <a href="xxreal_0.html#NR4" target="_self">&gt;</a> 0
 ; <i><font color="Red">:: according to </font></i><a class="ref" href="xxreal_0.html#D6">XXREAL_0:def 6</a><br/>

<a NAME="E3:27_1_1"/><b>then </b>
<span class="p1">(<span class="default"><a href="xcmplx_0.html#K4">-</a> <font color="Maroon">c<sub>8</sub></font></span>)</span> <a href="xcmplx_0.html#K2">+</a> <span class="p1">(<span class="default"><a href="xcmplx_0.html#K4">-</a> <span class="p2">(<span class="default"><a href="xcmplx_0.html#K4">-</a> <font color="Maroon">c<sub>8</sub></font></span>)</span></span>)</span> <a href="xxreal_0.html#NR4" target="_self">&gt;</a> 0
 
<b>by </b><i><a class="txt" href="xreal_0.html#E1:27_1_1"><i><font color="Green">E28</font></i></a>, <a class="txt" href="xreal_0.html#E24"><i><font color="Green">Lemma19</font></i></a></i>;<br/>
<b>hence </b><a NAME="E4:27_1_1"/>
contradiction
 ;<br/>


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