Answer:
[tex]2r^{2} s - {r}^{3} s \: for \: r = 3 \: and \: s = - 2 \\ \\ (2 \times {3}^{2} \times ( - 2) )- ({3}^{3} \times ( - 2) ) = \\ \\( 2 \times 9 \times ( - 2) )-( 27 \times ( - 2) )= \ \ \\ (18 \times ( - 2)) - (27 \times ( - 2)) = \\ - 36 \: - \: ( - 54) = \\ - 36 + 54 = 18[/tex]
