Ответ:

1) y(x+1) + z(x+1)= (y+z)(x+1)

2)y(x-1) + z(x-1) = (y+z)(x-1)

3)m(k+1) + n(k+1)=(m+n)(k+1)

4)m(1-k)+n(k-1)=(m-n)(1-k)

5)m(1-k)+n(k-1)=(m+n)(1-k)

6)m(-1+k)+n(k-1)=(m+n)(k-1)

7)n(m+5)+k(m+5)=(n+k)(m+5)

8)n(m-2)+k(-2+m)=(n+k)(m-2)