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 86 × 74.
- 2.If a + b = 9 and ab = 20, what is a² + b²?
- 3.Use a² − b² = (a + b)(a − b) to find 92² − 14².
- 4.Use (a + b)² = a² + 2ab + b² to find 22².
- 5.Use a² − b² = (a + b)(a − b) to find 52² − 12².
- 6.Use (a + b)(a − b) = a² − b² to find 57 × 43.
- 7.Use (a − b)² = a² − 2ab + b² to find 75².
- 8.Use a² − b² = (a + b)(a − b) to find 56² − 44².
- 9.Find the value of x² − 2xy + y² when x = 12 and y = 3.
- 10.Use (a + b)² = a² + 2ab + b² to find 44².
- 11.Use (a + b)(a − b) = a² − b² to find 27 × 13.
- 12.If a − b = 7 and ab = 44, what is a² + b²?
- 13.Find the value of x² − y² when x = 12 and y = 4.
- 14.Use (a + b)² = a² + 2ab + b² to find 38².
- 15.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 16.If a − b = 1 and ab = 2, what is a² + b²?
- 17.Use a² − b² = (a + b)(a − b) to find 40² − 19².
- 18.If a + b = 7 and ab = 10, what is a² + b²?
- 19.Use a² − b² = (a + b)(a − b) to find 22² − 1².
- 20.Use a² − b² = (a + b)(a − b) to find 59² − 53².
- 21.Use (a + b)² = a² + 2ab + b² to find 63².
- 22.If a + b = 3 and ab = 2, what is a² + b²?
- 23.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 24.Use (a + b)² = a² + 2ab + b² to find 85².
- 25.Use (a + b)² = a² + 2ab + b² to find 16².
- 26.Find the value of x² + 2xy + y² when x = 11 and y = 1.
- 27.Use (a + b)(a − b) = a² − b² to find 31 × 29.
- 28.Use (a − b)² = a² − 2ab + b² to find 35².
- 29.Use (a − b)² = a² − 2ab + b² to find 31².
- 30.Use (a + b)² = a² + 2ab + b² to find 109².
- 31.Use (a + b)² = a² + 2ab + b² to find 101².
- 32.If a − b = 3 and ab = 54, what is a² + b²?
- 33.Use a² − b² = (a + b)(a − b) to find 97² − 68².
- 34.If a + b = 15 and ab = 50, what is a² + b²?
- 35.Use (a + b)² = a² + 2ab + b² to find 99².
- 36.Use (a − b)² = a² − 2ab + b² to find 94².
- 37.Use (a + b)² = a² + 2ab + b² to find 23².
- 38.Find the value of x² + 2xy + y² when x = 13 and y = 12.
- 39.Use (a + b)² = a² + 2ab + b² to find 12².
- 40.If a − b = 4 and ab = 5, what is a² + b²?
Answer key
- 6364
- 41
- 8268
- 484
- 2560
- 2451
- 5625
- 1200
- 81
- 1936
- 351
- 137
- 128
- 1444
- 391
- 5
- 1239
- 29
- 483
- 672
- 3969
- 5
- 4899
- 7225
- 256
- 144
- 899
- 1225
- 961
- 11881
- 10201
- 117
- 4785
- 125
- 9801
- 8836
- 529
- 625
- 144
- 26
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