Question

(í) (x + 3) (x – 3) (x + 4) (x - 4)​

Answer 1

$(x + 3)(x - 3(x + 4)(x - 4) \\ ( {x}^{2} - 3x + 3x - 9)( {x}^{2} - 4x + 4x + 16) \\ ({x}^{2} - x - 9)( {x}^{2} - x + 16) \\ (x - 9)(x + 16)$

i hope it is right

Answer 2

Answer:

(x2 - 9)(x2-16)

x2 (x2-16)-9(x2-16)

x4 - 16x2- 9x2+ 144

x4 - 25x2 + 144

Now u can solve it By middle term split