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 91 × 89.
- 2.Use (a + b)(a − b) = a² − b² to find 78 × 62.
- 3.Find the value of x² − 2xy + y² when x = 8 and y = 5.
- 4.Use (a + b)² = a² + 2ab + b² to find 22².
- 5.Use (a − b)² = a² − 2ab + b² to find 92².
- 6.Use (a + b)(a − b) = a² − b² to find 94 × 86.
- 7.If a − b = 2 and ab = 48, what is a² + b²?
- 8.Use (a + b)(a − b) = a² − b² to find 79 × 61.
- 9.If a − b = 1 and ab = 72, what is a² + b²?
- 10.If a − b = 1 and ab = 30, what is a² + b²?
- 11.Use (a + b)(a − b) = a² − b² to find 68 × 52.
- 12.Use (a + b)² = a² + 2ab + b² to find 16².
- 13.Use (a + b)(a − b) = a² − b² to find 22 × 18.
- 14.Use (a − b)² = a² − 2ab + b² to find 25².
- 15.Find the value of x² − 2xy + y² when x = 4 and y = 3.
- 16.Use (a + b)² = a² + 2ab + b² to find 73².
- 17.Use (a − b)² = a² − 2ab + b² to find 43².
- 18.Use (a + b)(a − b) = a² − b² to find 107 × 93.
- 19.Find the value of x² − 2xy + y² when x = 13 and y = 10.
- 20.If a + b = 7 and ab = 12, what is a² + b²?
- 21.If a + b = 7 and ab = 10, what is a² + b²?
- 22.Find the value of x² + 2xy + y² when x = 10 and y = 5.
- 23.Use (a − b)² = a² − 2ab + b² to find 72².
- 24.Use a² − b² = (a + b)(a − b) to find 20² − 8².
- 25.Use (a + b)(a − b) = a² − b² to find 73 × 67.
- 26.Use a² − b² = (a + b)(a − b) to find 22² − 5².
- 27.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 28.Use (a + b)² = a² + 2ab + b² to find 63².
- 29.Use (a − b)² = a² − 2ab + b² to find 99².
- 30.If a + b = 12 and ab = 35, what is a² + b²?
- 31.Find the value of x² − 2xy + y² when x = 3 and y = 1.
- 32.Use (a + b)(a − b) = a² − b² to find 83 × 77.
- 33.Find the value of x² − y² when x = 8 and y = 2.
- 34.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 35.If a + b = 3 and ab = 2, what is a² + b²?
- 36.Use (a + b)² = a² + 2ab + b² to find 94².
- 37.Use (a − b)² = a² − 2ab + b² to find 83².
- 38.If a + b = 23 and ab = 132, what is a² + b²?
- 39.Use (a + b)² = a² + 2ab + b² to find 108².
- 40.Use (a + b)² = a² + 2ab + b² to find 85².
Answer key
- 8099
- 4836
- 9
- 484
- 8464
- 8084
- 100
- 4819
- 145
- 61
- 3536
- 256
- 396
- 625
- 1
- 5329
- 1849
- 9951
- 9
- 25
- 29
- 225
- 5184
- 336
- 4891
- 459
- 864
- 3969
- 9801
- 74
- 4
- 6391
- 60
- 875
- 5
- 8836
- 6889
- 265
- 11664
- 7225
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