Factorise:
4x4−x2−12x−36
4x4−x2−12x−36⇒4x4−(x2+12x+36)⇒4x4−(x+6)2⇒(2x2)2−(x+6)2⇒(2x2+(x+6))(2x2−(x+6))⇒(2x2+x+6)(2x2−x−6)⇒(2x2+x+6)(2x2−4x+3x−6)⇒(2x2+x+6)(2x(x−2)+3(x−2))⇒(2x2+x+6)(2x+3)(x−2)
Factorise: x2+12x+36.