1) (y²- 2y)² = y^4 - 4y³ + 4y²
2) (- 7x + 3y³ )² = 49x² - 42xy³ + 9y^6
3) ( - 5 - 2a)² = 25 + 10a + 4a²
4) (y + x - 2)² = y² + 2xy - 4y + x² - 4x + 4
5) (3a + 2b)²(3a - 2b)² = (9a² - 4b²)(9a² - 4b²) = 81a^4 - 36a²b² - 36a²b² + 16b^4 = 81 a^4 - 72 a²b² + 16b^4