Первый
(5x² + 2y²)² - (5x² + 2y²)(5x² - 2y²) = (5x² + 2y²)(5x² + 2y² - 5x² + 2y²) =
= (5x² + 2y²) * 4y² = 20x²y² + 8y⁴
Второй
(5x² + 2y²)² - (5x² + 2y²)(5x² - 2y²) = 25x⁴ + 20x²y² + 4y⁴ - 25x⁴ + 4y⁴ =
= 20x²y² + 8y⁴
Первый
(5x² + 2y²)² - (5x² + 2y²)(5x² - 2y²) = (5x² + 2y²)(5x² + 2y² - 5x² + 2y²) =
= (5x² + 2y²) * 4y² = 20x²y² + 8y⁴
Второй
(5x² + 2y²)² - (5x² + 2y²)(5x² - 2y²) = 25x⁴ + 20x²y² + 4y⁴ - 25x⁴ + 4y⁴ =
= 20x²y² + 8y⁴