Question

Простите выражения (3m-n)^3-(n+3m)^3

Answer 1

(3m-n)³-(n+3m)³=

27m³-3*9m²n+3*3mn²-n³

-n³-27m²n-9mn²-27m³

=-54m²n-2n³

Answer 2

$(3m - n) {}^{3} - (n + 3m) {}^{3} = \\ = 27m {}^{3} - 27m {}^{2} n + 9mn {}^{2} - n {}^{3} - \\ - (n {}^{3} + 9mn {}^{2} + 27m {}^{2} n + 27m {}^{3} ) = \\ = 27m {}^{3} - 27m {}^{2} n + 9mn {}^{2} - n {}^{3} - \\ - n {}^{3} - 9mn {}^{2} - 27m {}^{2} n - 27m {}^{3}= \\ = - 54m {}^{2} n - 2n {}^{3}$