[tex] {x}^{3} -3 y {}^{2} = ( -3 ) {}^{3} -3 ( - \frac{1}{3} ) {}^{2} = - 27 - 3 \times \frac{1}{9} = - 27 - \frac{1}{3} = - 27 \frac{1}{3} [/tex]