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 a² − b² = (a + b)(a − b) to find 53² − 49².
- 2.Use a² − b² = (a + b)(a − b) to find 98² − 26².
- 3.Use a² − b² = (a + b)(a − b) to find 55² − 5².
- 4.Use (a − b)² = a² − 2ab + b² to find 79².
- 5.Use (a + b)² = a² + 2ab + b² to find 15².
- 6.Find the value of x² − y² when x = 15 and y = 1.
- 7.Use a² − b² = (a + b)(a − b) to find 72² − 27².
- 8.Find the value of x² + 2xy + y² when x = 11 and y = 6.
- 9.Find the value of x² − y² when x = 3 and y = 1.
- 10.Find the value of x² + 2xy + y² when x = 10 and y = 4.
- 11.Find the value of x² − y² when x = 11 and y = 6.
- 12.Use (a + b)(a − b) = a² − b² to find 109 × 91.
- 13.Use a² − b² = (a + b)(a − b) to find 36² − 3².
- 14.Use a² − b² = (a + b)(a − b) to find 22² − 18².
- 15.Use (a + b)² = a² + 2ab + b² to find 85².
- 16.Use (a − b)² = a² − 2ab + b² to find 36².
- 17.Find the value of x² − 2xy + y² when x = 13 and y = 5.
- 18.Find the value of x² − 2xy + y² when x = 3 and y = 2.
- 19.If a + b = 8 and ab = 7, what is a² + b²?
- 20.Use (a + b)² = a² + 2ab + b² to find 19².
- 21.If a − b = 4 and ab = 21, what is a² + b²?
- 22.Use (a − b)² = a² − 2ab + b² to find 17².
- 23.Use a² − b² = (a + b)(a − b) to find 30² − 24².
- 24.Use (a + b)² = a² + 2ab + b² to find 53².
- 25.Use a² − b² = (a + b)(a − b) to find 62² − 2².
- 26.If a + b = 12 and ab = 27, what is a² + b²?
- 27.Use (a + b)² = a² + 2ab + b² to find 31².
- 28.Use a² − b² = (a + b)(a − b) to find 54² − 37².
- 29.Use (a − b)² = a² − 2ab + b² to find 23².
- 30.Use (a + b)² = a² + 2ab + b² to find 39².
- 31.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 32.Use a² − b² = (a + b)(a − b) to find 53² − 33².
- 33.Use (a + b)(a − b) = a² − b² to find 102 × 98.
- 34.Use (a − b)² = a² − 2ab + b² to find 22².
- 35.Use (a + b)(a − b) = a² − b² to find 32 × 28.
- 36.If a + b = 4 and ab = 3, what is a² + b²?
- 37.Find the value of x² − 2xy + y² when x = 13 and y = 11.
- 38.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 39.Find the value of x² + 2xy + y² when x = 11 and y = 7.
- 40.Use (a + b)² = a² + 2ab + b² to find 52².
Answer key
- 408
- 8928
- 3000
- 6241
- 225
- 224
- 4455
- 289
- 8
- 196
- 85
- 9919
- 1287
- 160
- 7225
- 1296
- 64
- 1
- 50
- 361
- 58
- 289
- 324
- 2809
- 3840
- 90
- 961
- 1547
- 529
- 1521
- 4896
- 1720
- 9996
- 484
- 896
- 10
- 4
- 2484
- 324
- 2704
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