Problem 1 - Olympiad

If a and b are positive integers and a > b, then the value of (a + b)(a - b) is

A. a^2 - b^2B. a^2 + b^2C. a^2 - 2ab + b^2D. a^2 + 2ab + b^2

Correct: A

Using the algebraic identity (a + b)(a - b) = a^2 - b^2, we can simplify the expression. This identity is derived from the fact that (a + b)(a - b) = a^2 - ab + ab - b^2, which simplifies to a^2 - b^2.