[tex](x ^ { 3 } +6x ^ { 2 } -9x-54) \div (x-3) = \frac{\left(x-3\right)\left(x+3\right)\left(x+6\right)}{x-3} = \left(x+3\right)\left(x+6\right) = x^{2}+9x+18 = [/tex]
