What is the completely factored form of x4 + 8x2 – 9? (x + 1)(x – 1)(x + 3)(x + 3) (x+1)(x+1)(x+3){x^2+9} (x2 – 1)(x + 3)(x – 3) (x + 1)(x + 1)(x + 3)(x + 3)