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 (a + b)² = a² + 2ab + b² to find 74².
- 2.If a + b = 3 and ab = 2, what is a² + b²?
- 3.Use a² − b² = (a + b)(a − b) to find 86² − 15².
- 4.If a − b = 2 and ab = 24, what is a² + b²?
- 5.Use a² − b² = (a + b)(a − b) to find 41² − 16².
- 6.If a − b = 1 and ab = 42, what is a² + b²?
- 7.If a − b = 7 and ab = 30, what is a² + b²?
- 8.Use (a + b)(a − b) = a² − b² to find 105 × 95.
- 9.Use (a + b)(a − b) = a² − b² to find 49 × 31.
- 10.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 11.Use (a + b)² = a² + 2ab + b² to find 43².
- 12.Use (a − b)² = a² − 2ab + b² to find 65².
- 13.Use a² − b² = (a + b)(a − b) to find 29² − 10².
- 14.Use a² − b² = (a + b)(a − b) to find 52² − 35².
- 15.Use (a − b)² = a² − 2ab + b² to find 58².
- 16.Use (a − b)² = a² − 2ab + b² to find 43².
- 17.Use (a − b)² = a² − 2ab + b² to find 72².
- 18.Find the value of x² − 2xy + y² when x = 5 and y = 1.
- 19.Use (a − b)² = a² − 2ab + b² to find 53².
- 20.Use (a − b)² = a² − 2ab + b² to find 38².
- 21.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 22.Use a² − b² = (a + b)(a − b) to find 40² − 3².
- 23.Use a² − b² = (a + b)(a − b) to find 74² − 71².
- 24.Use (a + b)(a − b) = a² − b² to find 39 × 21.
- 25.If a + b = 6 and ab = 5, what is a² + b²?
- 26.Use a² − b² = (a + b)(a − b) to find 74² − 10².
- 27.Use (a − b)² = a² − 2ab + b² to find 36².
- 28.Use (a + b)(a − b) = a² − b² to find 51 × 49.
- 29.Use a² − b² = (a + b)(a − b) to find 67² − 17².
- 30.Use a² − b² = (a + b)(a − b) to find 21² − 8².
- 31.If a + b = 5 and ab = 6, what is a² + b²?
- 32.If a − b = 10 and ab = 11, what is a² + b²?
- 33.Find the value of x² − 2xy + y² when x = 11 and y = 9.
- 34.Find the value of x² + 2xy + y² when x = 11 and y = 4.
- 35.Use (a − b)² = a² − 2ab + b² to find 26².
- 36.If a + b = 5 and ab = 4, what is a² + b²?
- 37.Use (a + b)(a − b) = a² − b² to find 58 × 42.
- 38.Use (a + b)(a − b) = a² − b² to find 27 × 13.
- 39.Find the value of x² + 2xy + y² when x = 5 and y = 2.
- 40.Use (a + b)² = a² + 2ab + b² to find 66².
Answer key
- 5476
- 5
- 7171
- 52
- 1425
- 85
- 109
- 9975
- 1519
- 25
- 1849
- 4225
- 741
- 1479
- 3364
- 1849
- 5184
- 16
- 2809
- 1444
- 1591
- 1591
- 435
- 819
- 26
- 5376
- 1296
- 2499
- 4200
- 377
- 13
- 122
- 4
- 225
- 676
- 17
- 2436
- 351
- 49
- 4356
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