1. (a-b)(a+b)=a2-b2
  2. (a-b)(a2+ab+b2)=a3-b3
  3. (a+b)(a2-ab+b2)=a3+b3
  4. (a+b)2=a2+2ab+b2
  5. (a-b)2=a2-ab+b2
  6. (a+b)3=a3+3a2b+3ab2+b3
  7. (a-b)3=a3-3a2b+3ab2-b3