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<a NAME="E1:15_1_1"/>
( 0 <a href="xxreal_0.html#NR3" target="_self">&lt;</a> <font color="Maroon">x</font> or 0 <a href="xxreal_0.html#NR4" target="_self">&gt;</a> <font color="Maroon">x</font> or <font color="Maroon">x</font> <a href="hidden.html#R1">=</a> 0 )
 
<b>by </b><i><a class="ref" href="real_1.html#D5">REAL_1:def 5</a></i>;<br/>
<b>hence </b><a NAME="E2:15_1_1"/>
 <a href="absvalue.html#K1" target="_self">sgn</a> <font color="Maroon">x</font> is <a href="xreal_0.html#V1">real</a>
 <b>by </b><i/>;<br/>


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