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<b>let </b><font color="Maroon">x0</font> be   <a href="real_1.html#NM1">Real</a>;<br/><b>let </b><font color="Maroon">x1</font> be   <a href="real_1.html#NM1">Real</a>;<br/><b>let </b><font color="Maroon">f</font> be   <a href="funct_2.html#NM1">Function</a> of  <a href="numbers.html#K1">REAL</a> , <a href="numbers.html#K1">REAL</a> ;<br/>





<b>assume </b><b>that </b><br/><a NAME="E1:47"/><i><font color="Green">E40</font></i>: 
<font color="Maroon">f</font> is <a href="funct_1.html#V3">constant</a>
 <b>and </b><br/><a NAME="E2:47"/><i><font color="Green">E41</font></i>: 
<font color="Maroon">x0</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">x1</font>
 ;<br/>

<a NAME="E3:47"/>
( <font color="Maroon">x0</font> <a href="hidden.html#R2">in</a>  <a href="numbers.html#K1">REAL</a>  &amp; <font color="Maroon">x1</font> <a href="hidden.html#R2">in</a>  <a href="numbers.html#K1">REAL</a>  )
 
;<br/>
<a NAME="E4:47"/><b>then </b>
( <font color="Maroon">x0</font> <a href="hidden.html#R2">in</a>  <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> &amp; <font color="Maroon">x1</font> <a href="hidden.html#R2">in</a>  <a href="relset_1.html#K4">dom</a> <font color="Maroon">f</font> )
 
<b>by </b><i><a class="ref" href="funct_2.html#D1">FUNCT_2:def 1</a></i>;<br/>
<a NAME="E5:47"/><b>then </b><i><font color="Green">E44</font></i>: 
<font color="Maroon">f</font> <a href="seq_1.html#K2">.</a> <font color="Maroon">x0</font> <a href="hidden.html#R1">=</a> <font color="Maroon">f</font> <a href="seq_1.html#K2">.</a> <font color="Maroon">x1</font>
 
<b>by </b><i><a class="ref" href="funct_1.html#D16">FUNCT_1:def 16</a>, </i>;<br/>
<span class="p1"><a href="diff_1.html#K12" target="_self">[!</a><span class="default"><font color="Maroon">f</font>,<font color="Maroon">x0</font>,<font color="Maroon">x1</font></span><a href="diff_1.html#K12" target="_self">!]</a></span> = 
<span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">f</font> <a href="seq_1.html#K2">.</a> <font color="Maroon">x0</font></span>)</span> <a href="real_1.html#K5">-</a> <span class="p2">(<span class="default"><font color="Maroon">f</font> <a href="seq_1.html#K2">.</a> <font color="Maroon">x1</font></span>)</span></span>)</span> <a href="real_1.html#K6">/</a> <span class="p1">(<span class="default"><font color="Maroon">x0</font> <a href="real_1.html#K5">-</a> <font color="Maroon">x1</font></span>)</span>
<b>by </b><i>, </i>
<br/>.= 
0
<b>by </b><i/>
;<br/>
<b>hence </b><a NAME="E7:47"/>
<span class="p1"><a href="diff_1.html#K12" target="_self">[!</a><span class="default"><font color="Maroon">f</font>,<font color="Maroon">x0</font>,<font color="Maroon">x1</font></span><a href="diff_1.html#K12" target="_self">!]</a></span> <a href="hidden.html#R1">=</a> 0
 ;<br/>


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