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<b>let </b><font color="Maroon">z</font> be  <a href="xcmplx_0.html#V1">complex</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>

<b>set </b><font color="Maroon">r</font> =  <a href="complex1.html#K3" target="_self">Re</a> <font color="Maroon">z</font>;<br/>
<b>set </b><font color="Maroon">i</font> =  <a href="complex1.html#K4" target="_self">Im</a> <font color="Maroon">z</font>;<br/>
<b>thus </b><a NAME="E1:14"/>
( <font color="Maroon">z</font> <a href="hidden.html#R1">=</a> 0 implies <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="complex1.html#K3" target="_self">Re</a> <font color="Maroon">z</font></span>)</span> <a href="square_1.html#K5">^2</a> </span>)</span> <a href="real_1.html#K3">+</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="complex1.html#K4" target="_self">Im</a> <font color="Maroon">z</font></span>)</span> <a href="square_1.html#K5">^2</a> </span>)</span> <a href="hidden.html#R1">=</a> 0 )
 <b>by </b><i/>;<br/>

<b>assume </b><a NAME="E2:14"/>
0 <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="complex1.html#K3" target="_self">Re</a> <font color="Maroon">z</font></span>)</span> <a href="square_1.html#K5">^2</a> </span>)</span> <a href="real_1.html#K3">+</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="complex1.html#K4" target="_self">Im</a> <font color="Maroon">z</font></span>)</span> <a href="square_1.html#K5">^2</a> </span>)</span>
 ;<br/>

<a NAME="E3:14"/><b>then </b>
(  <a href="complex1.html#K3" target="_self">Re</a> <font color="Maroon">z</font> <a href="hidden.html#R1">=</a> 0 &amp;  <a href="complex1.html#K4" target="_self">Im</a> <font color="Maroon">z</font> <a href="hidden.html#R1">=</a> 0 )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E4:14"/>
<font color="Maroon">z</font> <a href="hidden.html#R1">=</a> 0
 <b>by </b><i>, </i>;<br/>


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