Let us discuss some algebra identities and do its formula.

  • Identity I - (a + b) 2 = a 2 + b 2 + 2ab
  • Identity II - (a − b) 2 = a 2 + b 2 − 2ab
  • Identity III - a 2 − b 2 = (a − b) (a + b)
  • Identity IV -   (x + a) (x + b) = x 2 + (a + b) x + ab

 

See Algebra Formulas for full list of identities.

 

Let’s take examples of the identities

Identity I - (a + b) 2 = a 2 + b 2 + 2ab

(2 + 3) 2 = 2 2 + 3 2 + 2(2)(3)

5 2 = 4 + 9 + 12

25 = 25


Identity II - (a − b) 2 = a 2 + b 2 − 2ab

(2 – 3) 2 = 2 2 + 3 2 – 2(2)(3)

(–1) 2 = 4 + 9 – 12

1 = 13 – 12

1 = 1


Identity III - a 2 − b 2 = (a − b) (a + b)

2 2 – 3 2 = (2 – 3) (2 + 3)

4 – 9 = – 1  × 5

–5 = –5


Identity IV -   (x + a) (x + b) = x 2 + (a + b) x + ab

(10 + 2) (10 + 3) = 10 2 + (2 + 3)10 + 2 × 3

12 ×  13 = 100 + 5 × 10 + 6

156 = 100 + 50 + 6

156 = 156

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.