[tex]\Big(-\dfrac{3}{5}\Big)^3 = -\dfrac{3^3}{5^3} = \boxed{-\dfrac{27}{125}}[/tex]
[tex](-\frac{3^{3} }{5^{3} } ) \frac{3*3*3}{5*5*5} = - \frac{27}{125}[/tex]
