3) (a + 1)(a - 1) (a² + 1) = (a² - 1)(a² + 1) = a^4 - 1
б) (1 - 2b)(1+ 2b)(1 + 4b²) = (1 - 4b²)(1 + 4b²) = 1 - 16b^4
в) (2ab² + 3)(3 - 2ab²) + 4a²b^4 = 9 - 4a²b^4 + 4a²b^4 = 9
г) (a/2 - 5)(5 + a/2) + 25 = a²/4 - 25 + 25 = a²/4
д) (a+3)² + (a - 3)² = a² + 6a + 9 + a² - 6a + 9 = 2a² + 18 = 2(a² + 9)
е) (4a+b)² - (4a - b)² = (4a+b + 4a - b)(4a+b - 4a + b) = 8a*2b = 16 ab
ж) (2 - a/b)² - a²/b² = 4 - 4a/b + a²/b² - a²/b² = 4 - 4a/b = 4(1 - a/b)
з) (1 - 7b)² - (1 + 7b)² = (1 - 14b + 49b²) - (1 + 14b + 49b²) = 1 - 14b + 49b² -1 - 14b - 49b² = -28b