Verified answer

1) (x+y)(x²-xy+y²)

2) (x-y)(x²+xy+y²)

3) (m-n)(m²+mn+n²)

4) (m+n)(m-mn+n²)

5) (p+q)(p²-pq+q²)

6) (p-q)(p²+pq+q²)

7) (a+2)(a²-2a+4)

8) (a-2)(a²+2a+4)

9) (m+3)(m²-3m+9)

10) (n-3)(n²+3n+9)

11) (1-x)(1+x+x²)

12) (1+y)(1-y+y²)