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.If a − b = 10 and ab = 24, what is a² + b²?
- 2.Use (a + b)(a − b) = a² − b² to find 103 × 97.
- 3.Find the value of x² − y² when x = 11 and y = 6.
- 4.Use (a − b)² = a² − 2ab + b² to find 35².
- 5.Find the value of x² − 2xy + y² when x = 7 and y = 3.
- 6.If a − b = 3 and ab = 10, what is a² + b²?
- 7.Use (a + b)(a − b) = a² − b² to find 99 × 81.
- 8.Use (a + b)(a − b) = a² − b² to find 104 × 96.
- 9.Use a² − b² = (a + b)(a − b) to find 42² − 34².
- 10.Find the value of x² + 2xy + y² when x = 9 and y = 8.
- 11.Use a² − b² = (a + b)(a − b) to find 96² − 79².
- 12.Use (a − b)² = a² − 2ab + b² to find 37².
- 13.If a − b = 2 and ab = 120, what is a² + b²?
- 14.Use a² − b² = (a + b)(a − b) to find 96² − 36².
- 15.Use a² − b² = (a + b)(a − b) to find 31² − 22².
- 16.Use (a + b)² = a² + 2ab + b² to find 24².
- 17.Use (a − b)² = a² − 2ab + b² to find 73².
- 18.Use a² − b² = (a + b)(a − b) to find 23² − 21².
- 19.Use (a − b)² = a² − 2ab + b² to find 91².
- 20.Use (a − b)² = a² − 2ab + b² to find 17².
- 21.Use (a − b)² = a² − 2ab + b² to find 55².
- 22.Use (a + b)(a − b) = a² − b² to find 61 × 59.
- 23.Find the value of x² + 2xy + y² when x = 15 and y = 4.
- 24.Use (a + b)² = a² + 2ab + b² to find 102².
- 25.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 26.Use (a − b)² = a² − 2ab + b² to find 22².
- 27.If a + b = 3 and ab = 2, what is a² + b²?
- 28.Use a² − b² = (a + b)(a − b) to find 32² − 13².
- 29.Use a² − b² = (a + b)(a − b) to find 54² − 30².
- 30.Find the value of x² + 2xy + y² when x = 10 and y = 5.
- 31.Use a² − b² = (a + b)(a − b) to find 55² − 34².
- 32.Find the value of x² + 2xy + y² when x = 5 and y = 4.
- 33.If a + b = 16 and ab = 55, what is a² + b²?
- 34.Use (a + b)² = a² + 2ab + b² to find 65².
- 35.Use (a + b)(a − b) = a² − b² to find 98 × 82.
- 36.Use (a − b)² = a² − 2ab + b² to find 69².
- 37.Use a² − b² = (a + b)(a − b) to find 42² − 6².
- 38.Use (a + b)(a − b) = a² − b² to find 79 × 61.
- 39.Use (a + b)(a − b) = a² − b² to find 109 × 91.
- 40.Use (a − b)² = a² − 2ab + b² to find 59².
Answer key
- 148
- 9991
- 85
- 1225
- 16
- 29
- 8019
- 9984
- 608
- 289
- 2975
- 1369
- 244
- 7920
- 477
- 576
- 5329
- 88
- 8281
- 289
- 3025
- 3599
- 361
- 10404
- 4899
- 484
- 5
- 855
- 2016
- 225
- 1869
- 81
- 146
- 4225
- 8036
- 4761
- 1728
- 4819
- 9919
- 3481
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