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 27².
- 2.Use (a − b)² = a² − 2ab + b² to find 64².
- 3.Use (a + b)² = a² + 2ab + b² to find 32².
- 4.If a − b = 3 and ab = 10, what is a² + b²?
- 5.Use (a − b)² = a² − 2ab + b² to find 69².
- 6.If a + b = 3 and ab = 2, what is a² + b²?
- 7.Use (a − b)² = a² − 2ab + b² to find 65².
- 8.Use (a + b)² = a² + 2ab + b² to find 55².
- 9.Find the value of x² − y² when x = 5 and y = 2.
- 10.Use (a + b)(a − b) = a² − b² to find 31 × 29.
- 11.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 12.If a + b = 9 and ab = 14, what is a² + b²?
- 13.Use (a − b)² = a² − 2ab + b² to find 17².
- 14.Find the value of x² − 2xy + y² when x = 14 and y = 4.
- 15.Use a² − b² = (a + b)(a − b) to find 51² − 18².
- 16.If a + b = 17 and ab = 60, what is a² + b²?
- 17.Use a² − b² = (a + b)(a − b) to find 49² − 12².
- 18.Use (a + b)² = a² + 2ab + b² to find 33².
- 19.Use (a − b)² = a² − 2ab + b² to find 29².
- 20.Use a² − b² = (a + b)(a − b) to find 21² − 2².
- 21.Use (a − b)² = a² − 2ab + b² to find 32².
- 22.Use (a − b)² = a² − 2ab + b² to find 21².
- 23.Use (a + b)² = a² + 2ab + b² to find 15².
- 24.Use (a + b)² = a² + 2ab + b² to find 11².
- 25.Use (a − b)² = a² − 2ab + b² to find 74².
- 26.Use a² − b² = (a + b)(a − b) to find 49² − 28².
- 27.Use (a + b)(a − b) = a² − b² to find 73 × 67.
- 28.If a − b = 2 and ab = 15, what is a² + b²?
- 29.Use a² − b² = (a + b)(a − b) to find 30² − 6².
- 30.Use a² − b² = (a + b)(a − b) to find 53² − 45².
- 31.Use (a + b)² = a² + 2ab + b² to find 44².
- 32.If a + b = 16 and ab = 63, what is a² + b²?
- 33.Find the value of x² − 2xy + y² when x = 8 and y = 6.
- 34.Use (a − b)² = a² − 2ab + b² to find 81².
- 35.Use (a + b)² = a² + 2ab + b² to find 109².
- 36.Use a² − b² = (a + b)(a − b) to find 77² − 70².
- 37.Use a² − b² = (a + b)(a − b) to find 51² − 20².
- 38.Use (a − b)² = a² − 2ab + b² to find 52².
- 39.Use (a − b)² = a² − 2ab + b² to find 42².
- 40.Use (a + b)(a − b) = a² − b² to find 43 × 37.
Answer key
- 729
- 4096
- 1024
- 29
- 4761
- 5
- 4225
- 3025
- 21
- 899
- 2484
- 53
- 289
- 100
- 2277
- 169
- 2257
- 1089
- 841
- 437
- 1024
- 441
- 225
- 121
- 5476
- 1617
- 4891
- 34
- 864
- 784
- 1936
- 130
- 4
- 6561
- 11881
- 1029
- 2201
- 2704
- 1764
- 1591
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