please answer all the step wise step

factorise
1. a^2 - b^2 - 4a +4

2. x^2 -xy - 3x +2 +2y

3. 4x^2 - 4a^2 - 4a - 1

4. x^2 + 3x + 2 + ax + 2a

5. 7 ( x - 1/x )^2 + 15 ( x - 1/x ) + 2

6. 64 - 144x + 108x^2 - 27x^3

7. ab^2 - b ( a-c ) - c

8. p^2 - a ^2 - 2pr + r^2