We will do questions of these identities

  • Identity VI - (a + b) 3 = a 3 + b 3 + 3ab(a + b)
  • Identity VII -  (a − b) 3 = a 3 - b 3 - 3ab(a - b)

 

Check Algebra Formulas for full list of formulas

 

Lets take an example

Identity VI - (a + b) 3 = a 3 + b 3 + 3ab(a + b)

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

(5) 3 = 8 + 27 + 18 × 5

125 = 8 + 27 + 90

125 = 125

 

Identity VII -  (a − b)3 = a3 - b3 - 3ab(a - b)

(2 – 3)3 = 23 – 33 – 3(2)(3) (2 – 3)

(–1)3 = 8 – 27 – 18 × (–1)

–1 = 8 – 27 + 18

–1 = 26 – 27

–1 = –1

 

  1. Chapter 2 Class 9 Polynomials
  2. Concept wise
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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.