n></div><div class="line"><a name="l00087"></a><span class="lineno">   87</span>&#160;<span class="comment">= (2^(x+1) - 2^x)/((x+1) - (x))</span></div><div class="line"><a name="l00088"></a><span class="lineno">   88</span>&#160;<span class="comment">= 2^(x) * (2 - 1) / 1</span></div><div class="line"><a name="l00089"></a><span class="lineno">   89</span>&#160;<span class="comment">= 2^(x)</span></div><div class="line"><a name="l00090"></a><span class="lineno">   90</span>&#160;<span class="comment">b = 2^