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 83².
- 2.Find the value of x² − y² when x = 15 and y = 7.
- 3.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 4.Use (a + b)(a − b) = a² − b² to find 96 × 84.
- 5.Use (a + b)² = a² + 2ab + b² to find 22².
- 6.Use (a − b)² = a² − 2ab + b² to find 37².
- 7.Use a² − b² = (a + b)(a − b) to find 76² − 39².
- 8.Use (a − b)² = a² − 2ab + b² to find 52².
- 9.Find the value of x² + 2xy + y² when x = 13 and y = 5.
- 10.Use (a − b)² = a² − 2ab + b² to find 22².
- 11.Use (a + b)² = a² + 2ab + b² to find 15².
- 12.If a + b = 11 and ab = 28, what is a² + b²?
- 13.Use (a + b)(a − b) = a² − b² to find 22 × 18.
- 14.Find the value of x² − y² when x = 4 and y = 2.
- 15.If a + b = 13 and ab = 22, what is a² + b²?
- 16.If a + b = 8 and ab = 7, what is a² + b²?
- 17.Use a² − b² = (a + b)(a − b) to find 30² − 2².
- 18.If a − b = 8 and ab = 33, what is a² + b²?
- 19.Use (a + b)(a − b) = a² − b² to find 42 × 38.
- 20.Use (a + b)(a − b) = a² − b² to find 82 × 78.
- 21.Use (a − b)² = a² − 2ab + b² to find 16².
- 22.Use (a − b)² = a² − 2ab + b² to find 19².
- 23.Use (a + b)² = a² + 2ab + b² to find 47².
- 24.Use (a + b)² = a² + 2ab + b² to find 92².
- 25.If a + b = 15 and ab = 56, what is a² + b²?
- 26.If a + b = 15 and ab = 50, what is a² + b²?
- 27.Find the value of x² − y² when x = 9 and y = 7.
- 28.If a − b = 3 and ab = 28, what is a² + b²?
- 29.Use (a − b)² = a² − 2ab + b² to find 62².
- 30.Use (a + b)² = a² + 2ab + b² to find 107².
- 31.Use (a − b)² = a² − 2ab + b² to find 77².
- 32.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 33.Use (a − b)² = a² − 2ab + b² to find 47².
- 34.Use (a + b)² = a² + 2ab + b² to find 108².
- 35.Use (a + b)(a − b) = a² − b² to find 29 × 11.
- 36.Use a² − b² = (a + b)(a − b) to find 43² − 26².
- 37.Use (a + b)² = a² + 2ab + b² to find 69².
- 38.If a + b = 5 and ab = 4, what is a² + b²?
- 39.Use (a − b)² = a² − 2ab + b² to find 83².
- 40.Find the value of x² − 2xy + y² when x = 4 and y = 1.
Answer key
- 6889
- 176
- 1591
- 8064
- 484
- 1369
- 4255
- 2704
- 324
- 484
- 225
- 65
- 396
- 12
- 125
- 50
- 896
- 130
- 1596
- 6396
- 256
- 361
- 2209
- 8464
- 113
- 125
- 32
- 65
- 3844
- 11449
- 5929
- 4899
- 2209
- 11664
- 319
- 1173
- 4761
- 17
- 6889
- 9
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