2 (x - y)² - 2 (x + y)² - 4 (x - y)(x + y) =
1) 2 (x - y)² = 2 (x² - 2xy + y²) = 2x² - 4xy + 2y²
2) 2 (x + y)² = 2 (x² + 2xy + y²) = 2x² + 4xy + 2y²
3) 4 (x - y)(x + y) = 4 (x² - y²) = 4x² - 4y²
4) 2x² - 4xy + 2y² - 2x² - 4xy - 2y² - 4x² + 4y² = -4x² + 4y² - 8xy = 4y² - 8xy - 4x² = y² - 2xy - x²
Ответ: y² - 2xy - x²