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 75 × 65.
- 2.Use a² − b² = (a + b)(a − b) to find 33² − 9².
- 3.Use a² − b² = (a + b)(a − b) to find 40² − 27².
- 4.Use (a − b)² = a² − 2ab + b² to find 47².
- 5.Use (a − b)² = a² − 2ab + b² to find 13².
- 6.Use (a + b)² = a² + 2ab + b² to find 41².
- 7.If a − b = 4 and ab = 5, what is a² + b²?
- 8.Use (a − b)² = a² − 2ab + b² to find 86².
- 9.Use (a − b)² = a² − 2ab + b² to find 17².
- 10.Use a² − b² = (a + b)(a − b) to find 65² − 30².
- 11.Use (a + b)² = a² + 2ab + b² to find 59².
- 12.Use a² − b² = (a + b)(a − b) to find 90² − 61².
- 13.Use (a + b)² = a² + 2ab + b² to find 11².
- 14.Use (a + b)² = a² + 2ab + b² to find 27².
- 15.Use (a − b)² = a² − 2ab + b² to find 23².
- 16.Use a² − b² = (a + b)(a − b) to find 25² − 12².
- 17.Use a² − b² = (a + b)(a − b) to find 52² − 46².
- 18.Use (a + b)² = a² + 2ab + b² to find 78².
- 19.Use (a + b)(a − b) = a² − b² to find 95 × 85.
- 20.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 21.Use (a + b)(a − b) = a² − b² to find 102 × 98.
- 22.Use a² − b² = (a + b)(a − b) to find 28² − 2².
- 23.Use a² − b² = (a + b)(a − b) to find 37² − 16².
- 24.Find the value of x² + 2xy + y² when x = 11 and y = 4.
- 25.Use (a + b)(a − b) = a² − b² to find 68 × 52.
- 26.Use a² − b² = (a + b)(a − b) to find 65² − 33².
- 27.Use a² − b² = (a + b)(a − b) to find 70² − 36².
- 28.Find the value of x² − 2xy + y² when x = 9 and y = 1.
- 29.If a − b = 1 and ab = 20, what is a² + b²?
- 30.Find the value of x² − 2xy + y² when x = 3 and y = 1.
- 31.Use a² − b² = (a + b)(a − b) to find 40² − 11².
- 32.Use (a + b)² = a² + 2ab + b² to find 63².
- 33.Use (a + b)(a − b) = a² − b² to find 103 × 97.
- 34.Use (a + b)(a − b) = a² − b² to find 106 × 94.
- 35.Use a² − b² = (a + b)(a − b) to find 34² − 10².
- 36.If a − b = 1 and ab = 56, what is a² + b²?
- 37.If a + b = 16 and ab = 55, what is a² + b²?
- 38.Use (a − b)² = a² − 2ab + b² to find 61².
- 39.Use a² − b² = (a + b)(a − b) to find 32² − 10².
- 40.Use (a + b)(a − b) = a² − b² to find 34 × 26.
Answer key
- 4875
- 1008
- 871
- 2209
- 169
- 1681
- 26
- 7396
- 289
- 3325
- 3481
- 4379
- 121
- 729
- 529
- 481
- 588
- 6084
- 8075
- 2484
- 9996
- 780
- 1113
- 225
- 3536
- 3136
- 3604
- 64
- 41
- 4
- 1479
- 3969
- 9991
- 9964
- 1056
- 113
- 146
- 3721
- 924
- 884
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