Решите пж срочно!!!! 50 баллов

Решите задачу:

$1. - 21b {}^{3} - 14b {}^{2} = - 7b {}^{2} (3b + 2) \\ mn + 3m - n {}^{2} - 3n = (n + 3)(m - n) \\ 81a {}^{2} - b {}^{2} = (9a - b)(9a + b) \\ 3y {}^{3} - 36y {}^{2} + 108y = 3y(y - 6) {}^{2} \\ 2. \frac{12a {}^{2}b + 8ab {}^{2} }{9a {}^{2} - 4b {}^{2} } = \frac{4ab(3a + 2b)}{(3a - 2b)(3a + 2b)} = \frac{4ab}{3a - 2b} \\ \frac{36c {}^{2} - 60c + 25}{25 - 36c {}^{2} } = \frac{(6c - 5) {}^{2} }{(5 - 6c)(5 + 6c)} = \frac{(6c - 5) {}^{2} }{ - (6c - 5)(5 + 6c)} \\ \frac{ - (6c - 5)}{5 + 6c} = - \frac{6c - 5}{5 + 6c} = \frac{5 - 6c}{5 + 6c} \\ 3.(x + 2) {}^{2} - 49 = 0 \\ x {}^{2} + 4x + 4 - 49 = 0 \\ x {}^{2} + 4x - 45 = 0 \\ d = 4 {}^{2} + 4 \times 45 = 16 + 180 = 196 \\ \sqrt{196} = 14 \\ x1 = \frac{ - 4 - 14}{2} = \frac{ - 18}{2} = - 9 \\ x2 = \frac{ - 4 + 14}{2} = \frac{10}{2} = 5 \\ 4.x {}^{2} + 14x - 51 = (x + 17)(x - 3) \\ x {}^{2} + 14x - 51 = x {}^{2} - 3x + 17x - 51 \\ x {}^{2} + 14x - 51 = x {}^{2} + 14x - 51 \\ 5. \frac{182 {}^{3} + 62 {}^{3} }{244} - 182 \times 62 \\ \frac{(182 + 62)(33124 - 11284 + 3844)}{244} - 11284 \\ \frac{244(33124 - 11284 + 3844)}{244} - 11284 \\ 33124 - 11284 + 3844 - 11284 = 14400$