1/(a + b)² = a² + 2ab + b²

2/(a + b)² = (a – b)² + 4ab

3/(a – b)² = a² – 2ab + b²

4/(a – b)² = (a + b)² – 4ab

5/a² + b² = (a + b)² – 2ab

6/a² + b² = (a – b)² + 2ab

7/a² – b² =(a + b)(a – b)

8/2(a²+b²) = (a+b)² + (a–b)²

9/4ab = (a + b)² -(a – b)²

10/ab = {(a+b)/2}²–{(a–b)/2}²

11/(a + b + c)² = a² + b² + c² +
2(ab + bc + ca)

12/(a + b)³ = a³ + 3a²b + 3ab²
+ b³

13/(a + b)³ = a³ + b³ + 3ab (a
+ b)

14/(a – b)³= a³ – 3a²b + 3ab²
– b³

15/a³ + b³ = (a + b) (a² – ab +
b²)

16/a³+ b³ = (a+b)³–3ab(a
+b)

17/a³-b³ = (a–b) (a²+ab+
b²)

18/a³–b³ = (a–b)³+3ab(a
–b)

19/(a+b+c)² = a²+b²+ c²+2(ab+bc+ca)