1. The problem asks to write Boussahia Sayeh's equation as $(x + y) \times (x - y)$. 2. This expression is a difference of squares formula, which states: $$ (a + b)(a - b) = a^2 - b^2 $$ 3. Applying this formula to $(x + y)(x - y)$, we get: $$ (x + y)(x - y) = x^2 - y^2 $$ 4. Therefore, the equation $(x + y)(x - y)$ simplifies to $x^2 - y^2$. 5. This is a fundamental algebraic identity useful for factoring and simplifying expressions involving squares.