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<div><b>hereby </b>
<div class="add"><b>assume </b><a NAME="E1:31_1_1_1"/><i><font color="Green">E19</font></i>: 
<font color="Maroon">c<sub>1</sub></font> is <a href="pythtrip.html#V3" target="_self">simplified</a>
 ;<br/><b>consider </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</sub></font>, <font color="Maroon">c<sub>4</sub></font> being   <a href="nat_1.html#NM1">Nat</a><b> such that </b><br/><a NAME="E3:31_1_1_1"/><i><font color="Green">E20</font></i>: 
( <span class="p1">(<span class="default"><font color="Maroon">c<sub>2</sub></font> <a href="pepin.html#K2">^2</a> </span>)</span> <a href="nat_1.html#K1">+</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>3</sub></font> <a href="pepin.html#K2">^2</a> </span>)</span> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>4</sub></font> <a href="pepin.html#K2">^2</a>  &amp; <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="domain_1.html#K8">{</a><span class="default"><font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>4</sub></font></span><a href="domain_1.html#K8">}</a></span> )
 <b>by </b><i><a class="ref" href="pythtrip.html#D4" target="_self">Def4</a></i>;<br/><b>take </b><font color="Maroon">c<sub>5</sub></font> = <font color="Maroon">c<sub>2</sub></font>;<br/><b>take </b><font color="Maroon">c<sub>6</sub></font> = <font color="Maroon">c<sub>3</sub></font>;<br/><b>thus </b><a NAME="E4:31_1_1_1"/>
<font color="Maroon">c<sub>5</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="pythtrip.html#E3:31_1_1_1"><i><font color="Green">E20</font></i></a>, <a class="ref" href="enumset1.html#D1">ENUMSET1:def 1</a></i>;<br/><b>thus </b><a NAME="E5:31_1_1_1"/>
<font color="Maroon">c<sub>6</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="pythtrip.html#E3:31_1_1_1"><i><font color="Green">E20</font></i></a>, <a class="ref" href="enumset1.html#D1">ENUMSET1:def 1</a></i>;<br/><div><a class="txt" onclick="hs2(this)" href="javascript:()" title="31_1_1_1_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">c<sub>7</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/><b>assume </b><a NAME="E1:31_1_1_1_1"/><i><font color="Green">E21</font></i>: 
( <font color="Maroon">c<sub>7</sub></font> <a href="nat_1.html#R1">divides</a> <font color="Maroon">c<sub>5</sub></font> &amp; <font color="Maroon">c<sub>7</sub></font> <a href="nat_1.html#R1">divides</a> <font color="Maroon">c<sub>6</sub></font> )
 ;<br/><a NAME="E2:31_1_1_1_1"/><b>then </b>
( <font color="Maroon">c<sub>7</sub></font> <a href="pepin.html#K2">^2</a>  <a href="nat_1.html#R1">divides</a> <font color="Maroon">c<sub>5</sub></font> <a href="pepin.html#K2">^2</a>  &amp; <font color="Maroon">c<sub>7</sub></font> <a href="pepin.html#K2">^2</a>  <a href="nat_1.html#R1">divides</a> <font color="Maroon">c<sub>6</sub></font> <a href="pepin.html#K2">^2</a>  )
 <b>by </b><i><a class="ref" href="pythtrip.html#T6" target="_self">Th6</a></i>;<br/><a NAME="E3:31_1_1_1_1"/><b>then </b>
<font color="Maroon">c<sub>7</sub></font> <a href="pepin.html#K2">^2</a>  <a href="nat_1.html#R1">divides</a> <font color="Maroon">c<sub>4</sub></font> <a href="pepin.html#K2">^2</a> 
 <b>by </b><i><a class="txt" href="pythtrip.html#E3:31_1_1_1"><i><font color="Green">E20</font></i></a>, <a class="ref" href="nat_1.html#T55">NAT_1:55</a></i>;<br/><a NAME="E4:31_1_1_1_1"/><b>then </b>
<font color="Maroon">c<sub>7</sub></font> <a href="nat_1.html#R1">divides</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="ref" href="pythtrip.html#T6" target="_self">Th6</a></i>;<br/><a NAME="E5:31_1_1_1_1"/><b>then </b>
for <font color="Olive">b<sub>1</sub></font> being  <a href="nat_1.html#NM1">Nat</a> st <font color="Olive">b<sub>1</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font> holds <br/><font color="Maroon">c<sub>7</sub></font> <a href="nat_1.html#R1">divides</a> <font color="Olive">b<sub>1</sub></font>
 <b>by </b><i><a class="txt" href="pythtrip.html#E3:31_1_1_1"><i><font color="Green">E20</font></i></a>, <a class="txt" href="pythtrip.html#E1:31_1_1_1_1"><i><font color="Green">E21</font></i></a>, <a class="ref" href="enumset1.html#D1">ENUMSET1:def 1</a></i>;<br/><b>hence </b><a NAME="E6:31_1_1_1_1"/>
<font color="Maroon">c<sub>7</sub></font> <a href="hidden.html#R1">=</a> 1
 <b>by </b><i><a class="txt" href="pythtrip.html#E1:31_1_1_1"><i><font color="Green">E19</font></i></a>, <a class="ref" href="pythtrip.html#D7" target="_self">Def7</a></i>;<br/></div><b>end;</b></div><b>hence </b><a NAME="E7:31_1_1_1"/>
<font color="Maroon">c<sub>5</sub></font>,<font color="Maroon">c<sub>6</sub></font> <a href="int_2.html#R2">are_relative_prime</a> 
 <b>by </b><i><a class="ref" href="pythtrip.html#D1" target="_self">Def1</a></i>;<br/></div>
<b>end;</b></div>

<b>assume </b><a NAME="E2:31_1_1"/>
ex <font color="Olive">b<sub>1</sub></font>, <font color="Olive">b<sub>2</sub></font> being  <a href="nat_1.html#NM1">Nat</a> st <br/>( <font color="Olive">b<sub>1</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font> &amp; <font color="Olive">b<sub>2</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font> &amp; <font color="Olive">b<sub>1</sub></font>,<font color="Olive">b<sub>2</sub></font> <a href="int_2.html#R2">are_relative_prime</a>  )
 ;<br/>

<b>then consider </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</sub></font> being   <a href="nat_1.html#NM1">Nat</a><b> such that </b><br/><a NAME="E4:31_1_1"/><i><font color="Green">E19</font></i>: 
( <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font> &amp; <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font> &amp; <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> <a href="int_2.html#R2">are_relative_prime</a>  )
 ;<br/>
<a NAME="E5:31_1_1"/><i><font color="Green">E20</font></i>: 
<font color="Maroon">c<sub>2</sub></font> <a href="nat_1.html#K8">hcf</a> <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a> 1
 
<b>by </b><i><a class="txt" href="pythtrip.html#E4:31_1_1"><i><font color="Green">E19</font></i></a>, <a class="ref" href="int_2.html#D6">INT_2:def 6</a></i>;<br/>
<b>let </b><font color="Maroon">c<sub>4</sub></font> be   <a href="nat_1.html#NM1">Nat</a>; <i><font color="Red">:: according to </font></i><a class="ref" href="pythtrip.html#D7" target="_self">PYTHTRIP:def 7</a><br/>

<b>assume </b><a NAME="E6:31_1_1"/>
for <font color="Olive">b<sub>1</sub></font> being  <a href="nat_1.html#NM1">Nat</a> st <font color="Olive">b<sub>1</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>1</sub></font> holds <br/><font color="Maroon">c<sub>4</sub></font> <a href="nat_1.html#R1">divides</a> <font color="Olive">b<sub>1</sub></font>
 ;<br/>

<a NAME="E7:31_1_1"/><b>then </b>
( <font color="Maroon">c<sub>4</sub></font> <a href="nat_1.html#R1">divides</a> <font color="Maroon">c<sub>2</sub></font> &amp; <font color="Maroon">c<sub>4</sub></font> <a href="nat_1.html#R1">divides</a> <font color="Maroon">c<sub>3</sub></font> )
 
<b>by </b><i><a class="txt" href="pythtrip.html#E4:31_1_1"><i><font color="Green">E19</font></i></a></i>;<br/>
<a NAME="E8:31_1_1"/><b>then </b>
<font color="Maroon">c<sub>4</sub></font> <a href="nat_1.html#R1">divides</a> 1
 
<b>by </b><i><a class="txt" href="pythtrip.html#E5:31_1_1"><i><font color="Green">E20</font></i></a>, <a class="ref" href="nat_1.html#D5">NAT_1:def 5</a></i>;<br/>
<b>hence </b><a NAME="E9:31_1_1"/>
<font color="Maroon">c<sub>4</sub></font> <a href="hidden.html#R1">=</a> 1
 <b>by </b><i><a class="ref" href="wsierp_1.html#T20">WSIERP_1:20</a></i>;<br/>


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