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<b>let </b><font color="Maroon">x</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="numbers.html#K1">REAL</a> ;<br/>

<a NAME="E1:17"/>
 <a href="arytm_0.html#K1">+</a> <font color="Maroon">x</font>,<span class="p1">(<span class="default"><a href="arytm_0.html#K3">opp</a> <font color="Maroon">x</font></span>)</span> <a href="hidden.html#R1">=</a> 0
 
<b>by </b><i><a class="ref" href="arytm_0.html#D4">ARYTM_0:def 4</a></i>;<br/>
<a NAME="E2:17"/><b>then </b>
<font color="Maroon">x</font> <a href="real_1.html#K3">+</a> <span class="p1">(<span class="default"><a href="arytm_0.html#K3">opp</a> <font color="Maroon">x</font></span>)</span> <a href="hidden.html#R1">=</a> 0
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E3:17"/>
 <a href="arytm_0.html#K3">opp</a> <font color="Maroon">x</font> <a href="hidden.html#R1">=</a>  <a href="real_1.html#K1">-</a> <font color="Maroon">x</font>
 ;<br/>


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