Question 293591
{{{8x^3+4x^2-18x-9}}} Start with the given expression



{{{(8x^3+4x^2)+(-18x-9)}}} Group like terms



{{{4x^2(2x+1)-9(2x+1)}}} Factor out the GCF {{{4x^2}}} out of the first group. Factor out the GCF {{{-9}}} out of the second group



{{{(4x^2-9)(2x+1)}}} Since we have the common term {{{2x+1}}}, we can combine like terms



{{{(2x+3)(2x-3)(2x+1)}}} Now factor {{{4x^2-9}}} to get {{{(2x+3)(2x-3)}}} (difference of squares)



So {{{8x^3+4x^2-18x-9}}} factors to {{{(2x+3)(2x-3)(2x+1)}}}



In other words, {{{8x^3+4x^2-18x-9=(2x+3)(2x-3)(2x+1)}}}



This basically means that {{{8x^3+4x^2-18x-9=0}}} is equivalent to {{{(2x+3)(2x-3)(2x+1)=0}}}. I'll let you take it from here.