Step-by-step explanation:
The product of the sum of a and b and their difference:
(a + b)(a - b) = a² - b²
Proof:
L = (a + b)(a - b) use FOIL
L = (a)(a) + (a)(-b) + (b)(a) + (b)(-b)
L = a² - ab + ab - b² combine like terms
L = a² - b² + (-ab + ab)
L = a² - b²
R = a² - b²
L = R
