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Algebra: Expansions
(a + b)
2
(a + b)
2
= a
2
+ 2ab + b
2
(a − b)
2
(a − b)
2
= a
2
− 2ab + b
2
(a + b)(a − b)
(a + b)(a − b) = a
2
− b
2
(x + a)(x + b)
(x + a)(x + b) = x
2
+ (a+b)x + ab
(a + b)
3
(a + b)
3
= a
3
+ 3a
2
b + 3ab
2
+ b
3
(a − b)
3
(a − b)
3
= a
3
− 3a
2
b + 3ab
2
- b
3
(a + b + c)
2
(a + b + c)
2
= a
2
+ b
2
+ c
2
+ 2(ab + bc + ca)
