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 49 × 31.
- 2.Use (a + b)(a − b) = a² − b² to find 75 × 65.
- 3.If a − b = 2 and ab = 3, what is a² + b²?
- 4.Use (a + b)(a − b) = a² − b² to find 61 × 59.
- 5.If a − b = 10 and ab = 11, what is a² + b²?
- 6.Use (a + b)(a − b) = a² − b² to find 37 × 23.
- 7.If a + b = 12 and ab = 27, what is a² + b²?
- 8.Use a² − b² = (a + b)(a − b) to find 61² − 22².
- 9.Use (a − b)² = a² − 2ab + b² to find 93².
- 10.Use (a + b)(a − b) = a² − b² to find 55 × 45.
- 11.Use (a − b)² = a² − 2ab + b² to find 52².
- 12.Use (a − b)² = a² − 2ab + b² to find 75².
- 13.Use (a + b)(a − b) = a² − b² to find 41 × 39.
- 14.Use (a + b)² = a² + 2ab + b² to find 101².
- 15.Use (a − b)² = a² − 2ab + b² to find 23².
- 16.Find the value of x² − y² when x = 5 and y = 1.
- 17.Use (a + b)² = a² + 2ab + b² to find 26².
- 18.Use a² − b² = (a + b)(a − b) to find 81² − 63².
- 19.Use (a − b)² = a² − 2ab + b² to find 25².
- 20.Use (a + b)² = a² + 2ab + b² to find 86².
- 21.Use a² − b² = (a + b)(a − b) to find 76² − 53².
- 22.Find the value of x² − 2xy + y² when x = 9 and y = 1.
- 23.Use (a + b)(a − b) = a² − b² to find 38 × 22.
- 24.Use a² − b² = (a + b)(a − b) to find 40² − 21².
- 25.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 26.If a − b = 1 and ab = 6, what is a² + b²?
- 27.Use (a + b)² = a² + 2ab + b² to find 92².
- 28.Find the value of x² − 2xy + y² when x = 6 and y = 2.
- 29.Use (a + b)² = a² + 2ab + b² to find 24².
- 30.Use (a + b)(a − b) = a² − b² to find 64 × 56.
- 31.Use a² − b² = (a + b)(a − b) to find 55² − 34².
- 32.If a + b = 17 and ab = 60, what is a² + b²?
- 33.Use a² − b² = (a + b)(a − b) to find 62² − 7².
- 34.Use (a + b)² = a² + 2ab + b² to find 69².
- 35.Use a² − b² = (a + b)(a − b) to find 35² − 17².
- 36.Find the value of x² − 2xy + y² when x = 14 and y = 6.
- 37.Use a² − b² = (a + b)(a − b) to find 28² − 25².
- 38.Use (a + b)(a − b) = a² − b² to find 83 × 77.
- 39.If a − b = 3 and ab = 40, what is a² + b²?
- 40.Use a² − b² = (a + b)(a − b) to find 67² − 2².
Answer key
- 1519
- 4875
- 10
- 3599
- 122
- 851
- 90
- 3237
- 8649
- 2475
- 2704
- 5625
- 1599
- 10201
- 529
- 24
- 676
- 2592
- 625
- 7396
- 2967
- 64
- 836
- 1159
- 1551
- 13
- 8464
- 16
- 576
- 3584
- 1869
- 169
- 3795
- 4761
- 936
- 64
- 159
- 6391
- 89
- 4485
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