[tex](1\frac{9}{16}) ^{-\frac{3}{2} }=(\frac{25}{16}) ^{-\frac{3}{2} }=(\frac{16}{25}) ^{\frac{3}{2} }=(\sqrt{\frac{16}{25}}) ^3=(\frac{4}{5})^3=\frac{64}{125} \\\\\sqrt[3]{\frac{1}{27} } -\sqrt{1\frac{13}{36} }=\frac{1}{3} -\sqrt{\frac{49}{36} }=\frac{2}{6} -\frac{7}{6}=-\frac{5}{6}[/tex]
