Question

what are formula of algebra​

Answer 1

Algebraic Identities

Algebraic formulas are known as Algebraic Identities or simply, Identities.

A few Identities for Class 8 CBSE Board are listed below with their Proofs.

Identity 1: (a+b)² = a²  + b²  + 2ab

Taking LHS, (a+b)²  = (a+b)(a+b) = a²  + ab + ba + b²  = a²  + ab + ab + b²  = a²  + 2ab + b²  or a²  + b²  + 2ab.

Identity 2: (a-b)² = a²  + b²  - 2ab

Taking LHS, (a-b)²  = (a-b)(a-b) = a²  -ab - ab + (-b)²  = a²  - 2ab + b²  or a²  + b²  - 2ab.

Identity 3: (a+b)(a-b) = a²  - b²

Taking LHS, (a+b)(a-b) = a²  -ab + ab - b²  = a²  - b² .

Identity 4: (x+a)(x+b) = x²  + (a+b)x + ab

Taking LHS, (x+a)(x+b) = x²  + xb + xa + ab = x²  + (a+b)x + ab.