Question 1127209

 if {{{x^3+ax+b}}}  when {{{divided}}} by  {{{(x^2-1)}}}  is  {{{x+2}}}, then

when {{{(x^2-1)}}}  {{{multiplied by  {{{x+2}}} is {{{x^3+ax+b}}}

so, multiply {{{(x^2-1)(x+2)}}}

{{{x^3-x-x-2}}}

{{{x^3-2x-2}}} now compare to {{{x^3+ax+b}}}  and you see that {{{a=-2}}} and {{{b=-2}}}