Factorise completely: (^= squared)

1. 6+2x
2. xy-x
3. b(2x-y)-c(2x-y)
4. 15x-3x^
5. 2p(3-q)+3(q-3)
6. x^+xy+y^+yx
7. a^-16
8. 4y^-81
9. x^-9x+18
10. x^n-5xn=