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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <font color="Maroon">c<sub>2</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/>



<b>assume </b><a NAME="E1:29"/>
<font color="Maroon">c<sub>1</sub></font> <a href="idea_1.html#R1" target="_self">is_expressible_by</a> <font color="Maroon">c<sub>2</sub></font>
 ;<br/>

<a NAME="E2:29"/><b>then </b>
<font color="Maroon">c<sub>1</sub></font> <a href="xxreal_0.html#NR3" target="_self">&lt;</a> 2 <a href="series_1.html#K3">to_power</a> <font color="Maroon">c<sub>2</sub></font>
 
<b>by </b><i><a class="ref" href="idea_1.html#D3" target="_self">Def3</a></i>;<br/>
<a NAME="E3:29"/><b>then </b>
 <a href="idea_1.html#K8" target="_self">ChangeVal_2</a> <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font> <a href="xxreal_0.html#NR3" target="_self">&lt;</a> 2 <a href="series_1.html#K3">to_power</a> <font color="Maroon">c<sub>2</sub></font>
 
<b>by </b><i><a class="ref" href="idea_1.html#D8" target="_self">Def8</a></i>;<br/>
<b>hence </b><a NAME="E4:29"/>
 <a href="idea_1.html#K8" target="_self">ChangeVal_2</a> <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font> <a href="idea_1.html#R1" target="_self">is_expressible_by</a> <font color="Maroon">c<sub>2</sub></font>
 <b>by </b><i><a class="ref" href="idea_1.html#D3" target="_self">Def3</a></i>;<br/>


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