Evaluate the following integral using trigonometric substitution.

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{\sqrt[\phantom{2}]{9x^2-64}}{x^3}dx,x>\frac{8}{3}$

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{\sqrt[\phantom{2}]{9x^2-64}}{x^3}dx=$

$(Typean$ exact answer.$)$