Решение:
- \( (c+3) - x(c+3) = (c+3)(1-x) \)
- \( a(b-c) + d(c-b) = a(b-c) - d(b-c) = (b-c)(a-d) \)
- \( (x - y)^2 - a(y - x) = (x - y)^2 + a(x - y) = (x - y)((x - y) + a) = (x - y)(x - y + a) \)
Ответ: 1) \( (c+3)(1-x) \); 2) \( (b-c)(a-d) \); 3) \( (x - y)(x - y + a) \).