Important Problems on Numbers Formulas
Some Basic Formulas
- (a + b)(a - b) = (a2 - b2)
- (a + b)2 = (a2 + b2 + 2ab)
- (a2 - b2) = (a2 + b2 - 2ab)
- (a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ac)
- a3 + b3 = (a + b)(a2 - ab + b2)
- a3 - b3 = (a - b)(a2 + ab + b2)
- a3 + b3 + c3 - 3abc = (a + b + c)(a2 + b2 + c2 - ab -bc - ca)
- When a + b + c = 0, then a3 + b3 + c3 = 3abc.
