Помоги умоляю срочно,срочно,срочно

Решите задачу:

$1.(a - 3)(a + 5) = a {}^{2} + 5a - 3a - 15 = a {}^{2} + 2a - 15 \\ (4x - y)(5y + 3x) = 20xy + 12x {}^{2} - 5y {}^{2} - 3xy = 12x {}^{2} + 17xy 5y {}^{2} \\ (x - 3)(x {}^{2} - 2x + 7) = x {}^{3} - 2x {}^{2} + 7x - 3x {}^{2} + 6x - 21 = x { }^{ 3} - 5x {}^{2} + 13x - 21 \\ 2.(x + 3)(m - n) \\ 2x - 2y + ax - ay = 2(x - y) + a(x - y) = (2 + a)(x - y) \\ 3.(a + b)b - (a{}^{2} + b {}^{2} )(a - 2) = ab + b {}^{2} - (a {}^{3} - 2a {}^{2} + ab {}^{2} - 2b { }^{2} ) = ab + b {}^{2} - a { }^{ 3} + 2a {}^{2} - ab {}^{2} + 2b {}^{2} \\ ab + 3b {}^{2} - a {}^{3} + 2a { }^{2} - ab {}^{2} \\ 4.(x + y)(x + b) = x {}^{2} + (y + b)x + yb \\ x {}^{2} + xb + xy + yb = x {}^{2} + xy + bx + yb \\ 5.x(2 + x) = 0 \\ x = 0 \\ 2 + x = 0 \\ x = - 2 \\ 6.(a + 3)(a + 1) \\ d = 4 {}^{2} - 4 \times 3 = 16 - 12 = 4 \\ \sqrt{4} = 2 \\ x1 = \frac{ - 4 - 2}{2} = \frac{ - 6}{2} = - 3 \\ x2 = \frac{ - 4 + 2}{2} = \frac{ - 2}{2} = - 1$