Some Basic Formulas
1. (a+b)2 = a2+b2+2ab
2. (a-b)2 = a2+b2– 2ab
3. (a+b)2 – (a-b)2 = 4ab
4. (a+b)2 + (a-b)2 = 2(a2 + b2)
5. (a2 -b2) = (a+b)(a-b)
6. (a+b+c)2 = a2 +b2+c2+2(ab+bc+ca)
7. (a3+b3) = (a+b)(a2-ab+b2)
8. (a3– b3) = (a-b)(a2+ab+b2)
9. (a3– b3) = (a-b)(a2+ab+b2)
10. (a3+b3+c3 -3abc) = (a+b+c)(a2+b2+c2-ab-bc-ca)
11. If a+b+c=0, then a3+b3+c3 = 3abc.