Question 146143
Right idea, but you have a sign error.  Factor out {{{-3}}}, so that the resulting binomial is the <i> difference </i> of two squares, that is: {{{-3(x^2 - 81)}}}.  Your result should be:  {{{-3(x+9)(x-9)}}}.  The sum of two squares <i> never </i> factors; the roots of {{{x^2+a^2=0}}} are <i> always </i> imaginary.