(27)^-2/3+(1/256)^-3/4-(1/16)^-3/4=
27⁻²/³+(1/256)⁻³/⁴-(1/16)⁻³/⁴=(3)³*⁽⁻²/³⁾+(1/2)⁸*⁽⁻³/⁴⁾-(1/2)⁴*⁽⁻³/⁴⁾= =3⁻²+(1/2)⁻⁶-(1/2)⁻³=(1/3)²+2⁶-2³=1/9+64-8=56¹/₉.