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 64².
- 2.Use (a − b)² = a² − 2ab + b² to find 17².
- 3.Use (a + b)(a − b) = a² − b² to find 45 × 35.
- 4.Use (a + b)² = a² + 2ab + b² to find 12².
- 5.Use (a − b)² = a² − 2ab + b² to find 34².
- 6.Use (a − b)² = a² − 2ab + b² to find 73².
- 7.Use a² − b² = (a + b)(a − b) to find 24² − 3².
- 8.If a − b = 4 and ab = 77, what is a² + b²?
- 9.Use (a + b)(a − b) = a² − b² to find 102 × 98.
- 10.If a + b = 16 and ab = 55, what is a² + b²?
- 11.If a + b = 4 and ab = 3, what is a² + b²?
- 12.Use a² − b² = (a + b)(a − b) to find 20² − 2².
- 13.Use (a + b)² = a² + 2ab + b² to find 88².
- 14.Find the value of x² − 2xy + y² when x = 10 and y = 6.
- 15.Use (a + b)(a − b) = a² − b² to find 83 × 77.
- 16.Find the value of x² − y² when x = 15 and y = 12.
- 17.Use a² − b² = (a + b)(a − b) to find 21² − 12².
- 18.Use a² − b² = (a + b)(a − b) to find 59² − 25².
- 19.Use (a − b)² = a² − 2ab + b² to find 94².
- 20.Find the value of x² − y² when x = 5 and y = 1.
- 21.Use a² − b² = (a + b)(a − b) to find 99² − 91².
- 22.Find the value of x² + 2xy + y² when x = 10 and y = 8.
- 23.If a − b = 2 and ab = 48, what is a² + b²?
- 24.Use (a + b)(a − b) = a² − b² to find 38 × 22.
- 25.Use (a + b)² = a² + 2ab + b² to find 39².
- 26.Use a² − b² = (a + b)(a − b) to find 75² − 37².
- 27.Use (a − b)² = a² − 2ab + b² to find 22².
- 28.Use (a + b)² = a² + 2ab + b² to find 72².
- 29.If a + b = 13 and ab = 30, what is a² + b²?
- 30.Use a² − b² = (a + b)(a − b) to find 94² − 71².
- 31.Use (a − b)² = a² − 2ab + b² to find 33².
- 32.Use (a + b)(a − b) = a² − b² to find 42 × 38.
- 33.If a − b = 2 and ab = 99, what is a² + b²?
- 34.Use (a + b)² = a² + 2ab + b² to find 77².
- 35.Use a² − b² = (a + b)(a − b) to find 46² − 20².
- 36.Use (a − b)² = a² − 2ab + b² to find 45².
- 37.Use (a − b)² = a² − 2ab + b² to find 86².
- 38.Find the value of x² − 2xy + y² when x = 8 and y = 2.
- 39.If a + b = 3 and ab = 2, what is a² + b²?
- 40.Find the value of x² − 2xy + y² when x = 15 and y = 13.
Answer key
- 4096
- 289
- 1575
- 144
- 1156
- 5329
- 567
- 170
- 9996
- 146
- 10
- 396
- 7744
- 16
- 6391
- 81
- 297
- 2856
- 8836
- 24
- 1520
- 324
- 100
- 836
- 1521
- 4256
- 484
- 5184
- 109
- 3795
- 1089
- 1596
- 202
- 5929
- 1716
- 2025
- 7396
- 36
- 5
- 4
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