The equation given is incorrect. The given possible roots give the equation as x^4-4x^3-4x^2-24x+15=0 So x^4 +4x^3+6x^2+12x+9 cannot have the given roots. Solution The equation given is incorrect. The given possible roots give the equation as x^4-4x^3-4x^2-24x+15=0 So x^4 +4x^3+6x^2+12x+9 cannot have the given roots..