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.Use a² − b² = (a + b)(a − b) to find 89² − 60².
- 2.Use a² − b² = (a + b)(a − b) to find 37² − 5².
- 3.Use (a + b)² = a² + 2ab + b² to find 81².
- 4.Use (a − b)² = a² − 2ab + b² to find 45².
- 5.Use a² − b² = (a + b)(a − b) to find 20² − 2².
- 6.Find the value of x² + 2xy + y² when x = 13 and y = 11.
- 7.Use (a + b)² = a² + 2ab + b² to find 97².
- 8.Use (a − b)² = a² − 2ab + b² to find 81².
- 9.Use (a + b)² = a² + 2ab + b² to find 47².
- 10.If a − b = 7 and ab = 30, what is a² + b²?
- 11.If a + b = 5 and ab = 4, what is a² + b²?
- 12.Use (a + b)² = a² + 2ab + b² to find 107².
- 13.If a − b = 4 and ab = 5, what is a² + b²?
- 14.Use a² − b² = (a + b)(a − b) to find 87² − 13².
- 15.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 16.Use (a − b)² = a² − 2ab + b² to find 35².
- 17.Use (a − b)² = a² − 2ab + b² to find 49².
- 18.Find the value of x² − y² when x = 10 and y = 1.
- 19.Use (a − b)² = a² − 2ab + b² to find 78².
- 20.Use (a + b)² = a² + 2ab + b² to find 102².
- 21.Use (a − b)² = a² − 2ab + b² to find 31².
- 22.Use (a + b)² = a² + 2ab + b² to find 87².
- 23.Use (a + b)² = a² + 2ab + b² to find 74².
- 24.Use (a + b)² = a² + 2ab + b² to find 51².
- 25.Use a² − b² = (a + b)(a − b) to find 93² − 21².
- 26.If a − b = 8 and ab = 9, what is a² + b²?
- 27.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 28.If a + b = 12 and ab = 35, what is a² + b²?
- 29.Use a² − b² = (a + b)(a − b) to find 65² − 16².
- 30.If a − b = 7 and ab = 18, what is a² + b²?
- 31.If a − b = 3 and ab = 10, what is a² + b²?
- 32.Use (a + b)² = a² + 2ab + b² to find 26².
- 33.Use (a + b)² = a² + 2ab + b² to find 31².
- 34.Use (a + b)² = a² + 2ab + b² to find 67².
- 35.Use a² − b² = (a + b)(a − b) to find 40² − 19².
- 36.Use (a − b)² = a² − 2ab + b² to find 62².
- 37.If a + b = 4 and ab = 3, what is a² + b²?
- 38.Use (a + b)² = a² + 2ab + b² to find 91².
- 39.Use a² − b² = (a + b)(a − b) to find 99² − 9².
- 40.Find the value of x² − 2xy + y² when x = 3 and y = 2.
Answer key
- 4321
- 1344
- 6561
- 2025
- 396
- 576
- 9409
- 6561
- 2209
- 109
- 17
- 11449
- 26
- 7400
- 884
- 1225
- 2401
- 99
- 6084
- 10404
- 961
- 7569
- 5476
- 2601
- 8208
- 82
- 2484
- 74
- 3969
- 85
- 29
- 676
- 961
- 4489
- 1239
- 3844
- 10
- 8281
- 9720
- 1
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