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.If a − b = 1 and ab = 6, what is a² + b²?
- 2.Use (a + b)² = a² + 2ab + b² to find 11².
- 3.Use (a − b)² = a² − 2ab + b² to find 51².
- 4.Use (a + b)(a − b) = a² − b² to find 98 × 82.
- 5.Use (a + b)² = a² + 2ab + b² to find 98².
- 6.Use a² − b² = (a + b)(a − b) to find 68² − 57².
- 7.If a − b = 1 and ab = 20, what is a² + b²?
- 8.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 9.Use (a + b)(a − b) = a² − b² to find 68 × 52.
- 10.Use (a + b)² = a² + 2ab + b² to find 81².
- 11.Use a² − b² = (a + b)(a − b) to find 32² − 24².
- 12.Find the value of x² + 2xy + y² when x = 8 and y = 4.
- 13.Use a² − b² = (a + b)(a − b) to find 65² − 52².
- 14.If a + b = 3 and ab = 2, what is a² + b²?
- 15.Use (a + b)² = a² + 2ab + b² to find 67².
- 16.Use (a + b)² = a² + 2ab + b² to find 101².
- 17.Use (a + b)(a − b) = a² − b² to find 67 × 53.
- 18.Use a² − b² = (a + b)(a − b) to find 37² − 29².
- 19.If a − b = 4 and ab = 5, what is a² + b²?
- 20.Find the value of x² − 2xy + y² when x = 4 and y = 2.
- 21.Use (a + b)(a − b) = a² − b² to find 94 × 86.
- 22.Find the value of x² − 2xy + y² when x = 7 and y = 6.
- 23.If a − b = 4 and ab = 60, what is a² + b²?
- 24.If a + b = 11 and ab = 28, what is a² + b²?
- 25.Use (a + b)² = a² + 2ab + b² to find 102².
- 26.Use (a + b)(a − b) = a² − b² to find 55 × 45.
- 27.Use (a − b)² = a² − 2ab + b² to find 88².
- 28.Use (a + b)(a − b) = a² − b² to find 33 × 27.
- 29.Find the value of x² + 2xy + y² when x = 11 and y = 3.
- 30.Use (a + b)² = a² + 2ab + b² to find 36².
- 31.Use (a + b)² = a² + 2ab + b² to find 43².
- 32.Find the value of x² − 2xy + y² when x = 7 and y = 3.
- 33.Use (a + b)² = a² + 2ab + b² to find 93².
- 34.Use (a + b)(a − b) = a² − b² to find 66 × 54.
- 35.Use a² − b² = (a + b)(a − b) to find 51² − 32².
- 36.Find the value of x² − y² when x = 15 and y = 5.
- 37.Use a² − b² = (a + b)(a − b) to find 40² − 2².
- 38.If a + b = 10 and ab = 16, what is a² + b²?
- 39.If a + b = 14 and ab = 45, what is a² + b²?
- 40.Use (a − b)² = a² − 2ab + b² to find 89².
Answer key
- 13
- 121
- 2601
- 8036
- 9604
- 1375
- 41
- 6336
- 3536
- 6561
- 448
- 144
- 1521
- 5
- 4489
- 10201
- 3551
- 528
- 26
- 4
- 8084
- 1
- 136
- 65
- 10404
- 2475
- 7744
- 891
- 196
- 1296
- 1849
- 16
- 8649
- 3564
- 1577
- 200
- 1596
- 68
- 106
- 7921
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