(x - y)² - (x + y)² = _____?
(x - y)² - (x + y)² = _____?
Explanation
(x - y)^2 = x^2 - 2xy + y^2 and (x + y)^2 = x^2 + 2xy + y^2.
Subtracting these, we get: x^2 - 2xy + y^2 - (x^2 + 2xy + y^2) = x^2 - 2xy + y^2 - x^2 - 2xy - y^2 = -4xy.
(x - y)^2 = x^2 - 2xy + y^2 and (x + y)^2 = x^2 + 2xy + y^2.
Subtracting these, we get: x^2 - 2xy + y^2 - (x^2 + 2xy + y^2) = x^2 - 2xy + y^2 - x^2 - 2xy - y^2 = -4xy.