Answer
$\dfrac {422}{5}=84.4$
Work Step by Step
$\int ^{9}_{4}x\sqrt {x}dx=\int ^{9}_{4}x^{\frac {3}{2}}dx=\dfrac {1}{\dfrac {3}{2}+1}x^{\frac {3}{2}+1}]^{9}_{4}=\dfrac {2}{5}\times 9^{\frac {5}{2}}-\dfrac {2}{5}\times 4^{\frac {5}{2}}=\dfrac {422}{5}=84.4$
