1. (a+3)(b-7) 2.(8+3x)(2y-1) 3.(3x^2-1)(2x+1) 4.(5с-1)(с^2-5с+1) 5.-8(y-1)(y+5) 6.(3a+5)(3a-6)+30

1) (а + 3) * (b - 7) = a * b + a * (-7) + 3 * b + 3 * (-7) = ab - 7a + 3b - 21;

2) (8 + 3x) * (2y - 1) = 8 * 2y - 8 * 1 + 3x * 2y - 3x * 1 = 16y - 8 + 6xy - 3x;

3) (3x^2 - 1) * (2x + 1) = 3x^2 * 2x + 3x^2 * 1 - 1 * 2x - 1 * 1 = 6x^3 + 3x^2 - 2x - 1;

4) (5c - 1) * (c^2 - 5c + 1) = 5c * c^2 - 5c * 5c + 5c * 1 - 1 * c^2 + 1 * 5c - 1 * 1 = 5c^3 - 25c^2 + 5c - c^2 + 5c - 1 = 5c^3 - 26c^2 + 10c - 1;

5) -8 * (y - 1) * (y + 5) = -8 * (y^2 + 5y - y - 5) = -8y^2 - 40y + 8y + 40 = -8y^2 - 32y + 40;

6) (3a + 5) * (3a - 6) + 30 = 9a^2 - 18a + 15a - 30 + 30 = 9a^2 - 3a.