Step-by-step explanation:
Use FOIL Method
First - (3x^2)(x^2) =3x^4
Outer - (3x^2)(-4) = - 12x^2
Inner - (6)(x^2)=6x^2
Last - (6)(-4) = - 24
3x^4 - 12x^2 + 6x^2 -24
3x^4 - 6x^2 - 24
