Sagot :
1)
2 (x² + y)² - (x + y)² = 2x² + 2y² - (x² + 2xy + y²) = 2x² + 2y² - x² - 2xy - y² = ² - 2x + y² =
(x - y)²
2)
x² - y² = (x + y) (x - y) = x - y
x + y x + y
2 (x² + y)² - (x + y)² = 2x² + 2y² - (x² + 2xy + y²) = 2x² + 2y² - x² - 2xy - y² = ² - 2x + y² =
(x - y)²
2)
x² - y² = (x + y) (x - y) = x - y
x + y x + y
1) 2(a²+b²)-(a+b)²=(a-b)²
2a²+2b²-(a²+2ab+b²)=a²-2ab+b²
2a²+2b²-a²-2ab-b²=a²-2ab+b²
a²-2ab+b²=a²-2ab+b²
2) (a²-b²)/a+b=a-b
a-b=a-b
2a²+2b²-(a²+2ab+b²)=a²-2ab+b²
2a²+2b²-a²-2ab-b²=a²-2ab+b²
a²-2ab+b²=a²-2ab+b²
2) (a²-b²)/a+b=a-b
a-b=a-b