1.1. 16x² - y² = (4x-y)(4x+y)
1.2. 49a² - 81 = (7a-9)(7+81)
1.3. 1 - b⁴c² = (1 - b²c)(1 + b²c)
1.4. 2x² - 18 = 2(x² - 9) = 2(x-3)(x+3)
1.5. x² + 2xy + y² = (x+y)² = (x+y)(x+y)
1.6. 3x² - 6x + 3 = 3(x² - 2x + 1) = 3(x-1)² = 3(x-1)(x-1)
2.1. (a-5)(a+5) = a² - 5a + 5a - 25 = a² - 25
2.2. (8+3c)(3c-8) = (3c+8)(3c-8) = 9c² - 24c + 24c - 64 = 9c² - 64
2.3. (6+a)² = 36 + 2a + a²
2.4. (2+y³)² = 4 + 4y³ + y⁶
2.5. (2a+3)² - (2a+1)(2a-1) = 4a² + 12a + 9 - 4a² + 2a - 2a + 1 = 12a + 10
Удачи!