Class 8 Maths Worksheet: Algebraic Identities
The method (Split into easy parts): (a + b)² = a² + 2ab + b². (a − b)² = a² − 2ab + b². (a + b)(a − b) = a² − b²; so a² − b² = (a + b)(a − b). a² + b² = (a + b)² − 2ab = (a − b)² + 2ab.
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- 1.Find the value of x² − 2xy + y² when x = 3 and y = 2.
- 2.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 3.Use a² − b² = (a + b)(a − b) to find 22² − 9².
- 4.Use (a − b)² = a² − 2ab + b² to find 19².
- 5.If a + b = 6 and ab = 8, what is a² + b²?
- 6.Use (a + b)(a − b) = a² − b² to find 37 × 23.
- 7.If a + b = 8 and ab = 7, what is a² + b²?
- 8.Use a² − b² = (a + b)(a − b) to find 30² − 7².
- 9.Use (a − b)² = a² − 2ab + b² to find 58².
- 10.Use (a − b)² = a² − 2ab + b² to find 25².
- 11.Use a² − b² = (a + b)(a − b) to find 87² − 86².
- 12.Find the value of x² − 2xy + y² when x = 11 and y = 9.
- 13.Find the value of x² − y² when x = 15 and y = 9.
- 14.If a + b = 5 and ab = 6, what is a² + b²?
- 15.If a + b = 3 and ab = 2, what is a² + b²?
- 16.Use a² − b² = (a + b)(a − b) to find 21² − 13².
- 17.If a − b = 1 and ab = 20, what is a² + b²?
- 18.If a + b = 23 and ab = 132, what is a² + b²?
- 19.Use (a + b)(a − b) = a² − b² to find 33 × 27.
- 20.Find the value of x² + 2xy + y² when x = 11 and y = 1.
- 21.Use (a − b)² = a² − 2ab + b² to find 93².
- 22.If a − b = 3 and ab = 4, what is a² + b²?
- 23.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 24.Use a² − b² = (a + b)(a − b) to find 58² − 22².
- 25.Use (a − b)² = a² − 2ab + b² to find 54².
- 26.Use (a − b)² = a² − 2ab + b² to find 77².
- 27.Use (a + b)(a − b) = a² − b² to find 66 × 54.
- 28.Use (a + b)(a − b) = a² − b² to find 97 × 83.
- 29.Use (a + b)² = a² + 2ab + b² to find 109².
- 30.Use (a − b)² = a² − 2ab + b² to find 13².
- 31.Use (a + b)² = a² + 2ab + b² to find 56².
- 32.Use (a + b)(a − b) = a² − b² to find 31 × 29.
- 33.Use a² − b² = (a + b)(a − b) to find 79² − 71².
- 34.Use (a + b)² = a² + 2ab + b² to find 95².
- 35.Use a² − b² = (a + b)(a − b) to find 71² − 59².
- 36.Use (a + b)(a − b) = a² − b² to find 109 × 91.
- 37.Use (a + b)(a − b) = a² − b² to find 79 × 61.
- 38.Use (a + b)² = a² + 2ab + b² to find 29².
- 39.If a − b = 1 and ab = 132, what is a² + b²?
- 40.Use (a + b)² = a² + 2ab + b² to find 82².
Answer key
- 1
- 384
- 403
- 361
- 20
- 851
- 50
- 851
- 3364
- 625
- 173
- 4
- 144
- 13
- 5
- 272
- 41
- 265
- 891
- 144
- 8649
- 17
- 6336
- 2880
- 2916
- 5929
- 3564
- 8051
- 11881
- 169
- 3136
- 899
- 1200
- 9025
- 1560
- 9919
- 4819
- 841
- 265
- 6724
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