Question 677724
Start by factoring {{{x^2}}} from the first two terms and {{{-225}}} from the last two terms:

{{{x^2(x+1)-225(x+1)=0}}}

Factor the parenthesis {{{(x+1)}}}:

{{{(x^2-225)(x+1)=0}}}

{{{(x+15)(x-15)(x+1)=0}}}

Each parenthesis could be zero, so solutions are:

{{{x = -15}}}
{{{x = 15}}}
{{{x = -1}}}