Question 758310
Multiply your equation out and
collect like terms.
(x + 4)(x - 4) = 9
 x^2 - 16 = 9
 x^2 - 16 - 9 = 0
 x^2 - 25 = 0
     x = square root of 25
     x = +5, -5
Proof:
Put values of x in equation.
(x + 4)(x - 4) = 9
(+5 + 4)(+5 - 4) = 9
(-5 + 4)(-5 - 4) = 9
Proved.
Hope this helps.
:-)