Answer:
(a+4)(a-4)=a²-4² ITS LIKE THIS BECAUSE ITS AN IDENTITY,
⇒a²-16
Even when we solve it by the regular method of solving polynomials we get a²-16 as answer as there and thats the proof for the identity.
(a+b)(a-b)=a(a-4)+4(a-4)
⇒a²-4a+4a-16
⇒a²-16[NOTE:-4a+4a=0]
Thus we can see that a²-16 is the answer we get when we try to solve it by regular polynomial solution tooo.
And a²-16 is the polynomial from which we get (a+4)(a-4)