[tex](\frac{1}{16} z^{3} -\frac{9}{10} )^{2} =(\frac{1}{16} z^{3})^{2} -2*\frac{1}{16} z^{3}*\frac{9}{10} +(\frac{9}{10} )^{2}=\frac{1}{256} z^{6}-\frac{9}{80} z^{3}+\frac{81}{100}[/tex]