17. Factorize:
1) \(a^{2}+2 b^{2}-2 c^{2}+3 a b+a c\)
2) \(a^{2}-2 b^{2}-2 c^{2}-a b+5 b c-a c\).
17. 1) \((a+b-c)(a+2b+2c)\)
2) \((a-2b+c)(a+b-2c)\).

Hint. Each expression can be considered as a quadratic trinomial, for example, in terms of \(a\) and find its roots.