an> <span class="identifier">x</span><span class="special">)</span> <span class="special">-&gt;</span> <span class="keyword">double</span> <span class="special">{</span> <span class="keyword">return</span> <span class="special">(</span><span class="identifier">x</span> <span class="special">-</span> <span class="identifier">root1</span><span class="special">)</span> <span class="special">*</span> <span class="special">(</span><span class="identifier">x</span> <span class="special">-</span> <span class="iden