1. (a+b)²  =  a²+b²+2ab 2. a²-b² =  (a-b)(a+b) 3. a²+b² = (a+b)²-2ab 4. (a-b)² = a²+b²-2ab 5. (a+b+c)² = a²+b²+c²+2ab+2bc+2ca 6. (a-b-c)² = a²+b²+c²-2ab+2bc-2ca 7. (a+b)³ = a³+b³+3a²b+3ab²=a³+b³+3ab(a+b) 8. (a-b)³ = a³-b³-3a²b+3ab² 9. a³-b³ = (a-b)(a²+ab+b²) 10. a³+b³ = (a+b)(a²-ab+b²) 11. (a+b)⁴ = a⁴+4a³b+6a²b²+4ab³+b⁴ 12. (a-b)⁴ = a⁴-4a³b+6a²b²-4ab³+b⁴ 13....