Answer:
See below.
Explanation:
The next natural number is x+1.
( x - 1)(x + 1) = x^2 - 1.
Let a = x-1, b = x and c = x+1 ( as they are consecutive numbers).
Product of a and c = ac = x^2 - 1 (as above).
b^2 = x^2.
so ac = x^2 - 1 = b^2 - 1
ac = b^2 - 1