<?xml version="1.0"?>
<div class="add">

<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/>

<b>assume </b><a NAME="E1:93"/>
<font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a> 4
 ;<br/>

<a NAME="E2:93"/><b>then </b>
 <a href="power.html#K6">log</a> 2,<font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a>  <a href="power.html#K6">log</a> 2,<span class="p1">(<span class="default">2 <a href="square_1.html#K5">^2</a> </span>)</span>
 
<b>by </b><i><a class="ref" href="pre_ff.html#T12">PRE_FF:12</a></i>;<br/>
<a NAME="E3:93"/><b>then </b>
 <a href="power.html#K6">log</a> 2,<font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a>  <a href="power.html#K6">log</a> 2,<span class="p1">(<span class="default">2 <a href="series_1.html#K3">to_power</a> 2</span>)</span>
 
<b>by </b><i><a class="ref" href="power.html#T53">POWER:53</a></i>;<br/>
<a NAME="E4:93"/><b>then </b>
 <a href="power.html#K6">log</a> 2,<font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a> 2 <a href="real_1.html#K4">*</a> <span class="p1">(<span class="default"><a href="power.html#K6">log</a> 2,2</span>)</span>
 
<b>by </b><i><a class="ref" href="power.html#T63">POWER:63</a></i>;<br/>
<a NAME="E5:93"/><b>then </b>
 <a href="power.html#K6">log</a> 2,<font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a> 2 <a href="nat_1.html#K2">*</a> 1
 
<b>by </b><i><a class="ref" href="power.html#T60">POWER:60</a></i>;<br/>
<b>hence </b><a NAME="E6:93"/>
<font color="Maroon">c<sub>1</sub></font> <a href="real_1.html#K4">*</a> <span class="p1">(<span class="default"><a href="power.html#K6">log</a> 2,<font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a> 2 <a href="nat_1.html#K2">*</a> <font color="Maroon">c<sub>1</sub></font>
 <b>by </b><i><a class="ref" href="xreal_1.html#T66">XREAL_1:66</a></i>;<br/>


</div>
