Question

(x+3)(x-3) (x+4) (x-4)

Answer 1

$(x - 3)(x + 3)(x + 4)(x - 4) \\ = ({x}^{2} - {3}^{2} )( {x}^{2} - {4}^{2} ) \\ = ({x }^{2} - 9)( {x}^{2} - 16) \\ = {x}^{4} - 16 {x}^{2} - 9 {x}^{2} + 16 \times 9 \\ = {x}^{4} - 25 {x}^{2} + 144$