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)(a − b) = a² − b² to find 64 × 56.
- 3.Find the value of x² − y² when x = 7 and y = 2.
- 4.Use a² − b² = (a + b)(a − b) to find 76² − 52².
- 5.Find the value of x² + 2xy + y² when x = 12 and y = 6.
- 6.Use (a + b)² = a² + 2ab + b² to find 23².
- 7.Find the value of x² + 2xy + y² when x = 10 and y = 5.
- 8.Use a² − b² = (a + b)(a − b) to find 53² − 29².
- 9.If a + b = 21 and ab = 108, what is a² + b²?
- 10.Use (a − b)² = a² − 2ab + b² to find 69².
- 11.Use (a − b)² = a² − 2ab + b² to find 45².
- 12.If a − b = 2 and ab = 15, what is a² + b²?
- 13.Use (a − b)² = a² − 2ab + b² to find 37².
- 14.Use (a + b)² = a² + 2ab + b² to find 42².
- 15.If a − b = 3 and ab = 4, what is a² + b²?
- 16.Use (a + b)² = a² + 2ab + b² to find 14².
- 17.Use (a + b)² = a² + 2ab + b² to find 47².
- 18.Use (a + b)² = a² + 2ab + b² to find 94².
- 19.Use (a + b)² = a² + 2ab + b² to find 82².
- 20.Find the value of x² − y² when x = 11 and y = 10.
- 21.Use (a − b)² = a² − 2ab + b² to find 82².
- 22.Use (a − b)² = a² − 2ab + b² to find 11².
- 23.Use (a + b)² = a² + 2ab + b² to find 17².
- 24.Find the value of x² − y² when x = 15 and y = 3.
- 25.Use (a − b)² = a² − 2ab + b² to find 15².
- 26.Use (a + b)(a − b) = a² − b² to find 46 × 34.
- 27.Find the value of x² + 2xy + y² when x = 6 and y = 3.
- 28.If a − b = 7 and ab = 8, what is a² + b²?
- 29.Use (a + b)² = a² + 2ab + b² to find 29².
- 30.Use (a − b)² = a² − 2ab + b² to find 78².
- 31.Use (a + b)(a − b) = a² − b² to find 55 × 45.
- 32.Use (a − b)² = a² − 2ab + b² to find 33².
- 33.If a − b = 3 and ab = 10, what is a² + b²?
- 34.If a + b = 15 and ab = 54, what is a² + b²?
- 35.If a + b = 4 and ab = 3, what is a² + b²?
- 36.Use (a + b)² = a² + 2ab + b² to find 75².
- 37.If a − b = 1 and ab = 132, what is a² + b²?
- 38.Use (a + b)² = a² + 2ab + b² to find 103².
- 39.Use (a − b)² = a² − 2ab + b² to find 75².
- 40.If a + b = 11 and ab = 10, what is a² + b²?
Answer key
- 729
- 3584
- 45
- 3072
- 324
- 529
- 225
- 1968
- 225
- 4761
- 2025
- 34
- 1369
- 1764
- 17
- 196
- 2209
- 8836
- 6724
- 21
- 6724
- 121
- 289
- 216
- 225
- 1564
- 81
- 65
- 841
- 6084
- 2475
- 1089
- 29
- 117
- 10
- 5625
- 265
- 10609
- 5625
- 101
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