№1
1) 5a(a^4 - 6a^8 + 3) = 5a^5 - 30a^9 + 15a
2) (x + 4)(3x - 2) = 3x^2 + 12x - 2x - 8 = 3x^2 + 10x - 8
3) (6m + 5n)(7m - 3n) = 42m^2 + 35mn - 18mn - 15n^2 = 42m^2 + 17mn - 15n^2
4) (x + 5)(x^8 + x - 6) = x^9 + x^8 + x^2 + 5x - 6x - 30 = x^9 + x^8 + x^2 - x - 30
№2
1) 18xy - 6x^2 = 6x(3y - x)
2) 15a^6 - 3a^4 = 3a^4(5a^2 - 1)
3) 4x - 4y + cx - cy = 4(x - y) + c(x - y) = (x - y)(4 + c)