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)(a − b) = a² − b² to find 31 × 29.
- 2.Find the value of x² − 2xy + y² when x = 4 and y = 3.
- 3.Use (a + b)² = a² + 2ab + b² to find 45².
- 4.Find the value of x² − 2xy + y² when x = 13 and y = 10.
- 5.Find the value of x² − 2xy + y² when x = 5 and y = 2.
- 6.Use (a − b)² = a² − 2ab + b² to find 62².
- 7.Use (a + b)(a − b) = a² − b² to find 98 × 82.
- 8.Use (a + b)² = a² + 2ab + b² to find 17².
- 9.Find the value of x² + 2xy + y² when x = 15 and y = 1.
- 10.If a − b = 1 and ab = 12, what is a² + b²?
- 11.Use (a − b)² = a² − 2ab + b² to find 71².
- 12.Use (a − b)² = a² − 2ab + b² to find 33².
- 13.Use (a − b)² = a² − 2ab + b² to find 84².
- 14.If a + b = 12 and ab = 32, what is a² + b²?
- 15.Use (a − b)² = a² − 2ab + b² to find 27².
- 16.If a + b = 12 and ab = 35, what is a² + b²?
- 17.Find the value of x² − y² when x = 13 and y = 1.
- 18.Use (a + b)² = a² + 2ab + b² to find 76².
- 19.Use (a + b)(a − b) = a² − b² to find 51 × 49.
- 20.Use (a − b)² = a² − 2ab + b² to find 98².
- 21.Find the value of x² − 2xy + y² when x = 4 and y = 2.
- 22.Use (a + b)² = a² + 2ab + b² to find 39².
- 23.Use (a + b)² = a² + 2ab + b² to find 61².
- 24.Use (a + b)² = a² + 2ab + b² to find 41².
- 25.Use (a − b)² = a² − 2ab + b² to find 61².
- 26.Use a² − b² = (a + b)(a − b) to find 49² − 22².
- 27.Find the value of x² − 2xy + y² when x = 11 and y = 1.
- 28.Use a² − b² = (a + b)(a − b) to find 26² − 11².
- 29.Find the value of x² + 2xy + y² when x = 14 and y = 5.
- 30.If a + b = 8 and ab = 12, what is a² + b²?
- 31.Find the value of x² − 2xy + y² when x = 4 and y = 1.
- 32.Use (a + b)(a − b) = a² − b² to find 48 × 32.
- 33.Use (a + b)² = a² + 2ab + b² to find 62².
- 34.Use (a + b)(a − b) = a² − b² to find 45 × 35.
- 35.Use (a + b)(a − b) = a² − b² to find 55 × 45.
- 36.Use (a + b)(a − b) = a² − b² to find 38 × 22.
- 37.Use (a + b)(a − b) = a² − b² to find 89 × 71.
- 38.If a − b = 3 and ab = 18, what is a² + b²?
- 39.Use (a + b)² = a² + 2ab + b² to find 104².
- 40.Use a² − b² = (a + b)(a − b) to find 23² − 18².
Answer key
- 899
- 1
- 2025
- 9
- 9
- 3844
- 8036
- 289
- 256
- 25
- 5041
- 1089
- 7056
- 80
- 729
- 74
- 168
- 5776
- 2499
- 9604
- 4
- 1521
- 3721
- 1681
- 3721
- 1917
- 100
- 555
- 361
- 40
- 9
- 1536
- 3844
- 1575
- 2475
- 836
- 6319
- 45
- 10816
- 205
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