<PRE><B>Question 743526</B>
&lt;pre&gt;
            z&lt;sup&gt;4&lt;/sup&gt; - 9 = 0  

        (z&lt;sup&gt;2&lt;/sup&gt;)&lt;sup&gt;2&lt;/sup&gt; - 3&lt;sup&gt;2&lt;/sup&gt; = 0

  (z&lt;sup&gt;2&lt;/sup&gt; - 3)(z&lt;sup&gt;2&lt;/sup&gt; + 3) = 0

z&lt;sup&gt;2&lt;/sup&gt; - 3 = 0;   z&lt;sup&gt;2&lt;/sup&gt; + 3 = 0
    z&lt;sup&gt;2&lt;/sup&gt; = 3;       z&lt;sup&gt;2&lt;/sup&gt; = -3
     z = ą&amp;#8730;&lt;span style=&quot;text-decoration: overline&quot;&gt;3&lt;/span&gt;;      z = ą&amp;#8730;&lt;span style=&quot;text-decoration: overline&quot;&gt;-3&lt;/span&gt;
                   z = ąi&amp;#8730;&lt;span style=&quot;text-decoration: overline&quot;&gt;3&lt;/span&gt;

Four answers &amp;#8730;&lt;span style=&quot;text-decoration: overline&quot;&gt;3&lt;/span&gt;, -&amp;#8730;&lt;span style=&quot;text-decoration: overline&quot;&gt;3&lt;/span&gt;, i&amp;#8730;&lt;span style=&quot;text-decoration: overline&quot;&gt;3&lt;/span&gt;, -i&amp;#8730;&lt;span style=&quot;text-decoration: overline&quot;&gt;3&lt;/span&gt;

Edwin&lt;/pre&gt;  </PRE>