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.Find the value of x² + 2xy + y² when x = 11 and y = 9.
- 2.Use (a − b)² = a² − 2ab + b² to find 39².
- 3.Use (a − b)² = a² − 2ab + b² to find 67².
- 4.Use (a + b)² = a² + 2ab + b² to find 106².
- 5.Find the value of x² + 2xy + y² when x = 6 and y = 1.
- 6.Use (a − b)² = a² − 2ab + b² to find 72².
- 7.Use (a + b)² = a² + 2ab + b² to find 59².
- 8.Use (a − b)² = a² − 2ab + b² to find 93².
- 9.Find the value of x² − 2xy + y² when x = 12 and y = 2.
- 10.Use (a + b)(a − b) = a² − b² to find 32 × 28.
- 11.Use (a + b)² = a² + 2ab + b² to find 87².
- 12.Use a² − b² = (a + b)(a − b) to find 43² − 41².
- 13.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 14.Use (a + b)² = a² + 2ab + b² to find 42².
- 15.Use a² − b² = (a + b)(a − b) to find 82² − 59².
- 16.Use (a + b)² = a² + 2ab + b² to find 82².
- 17.Find the value of x² − 2xy + y² when x = 12 and y = 7.
- 18.If a − b = 1 and ab = 110, what is a² + b²?
- 19.Use (a + b)² = a² + 2ab + b² to find 24².
- 20.If a − b = 3 and ab = 18, what is a² + b²?
- 21.Use (a + b)² = a² + 2ab + b² to find 21².
- 22.Use (a + b)(a − b) = a² − b² to find 65 × 55.
- 23.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 24.If a − b = 4 and ab = 60, what is a² + b²?
- 25.Use (a + b)² = a² + 2ab + b² to find 85².
- 26.Use (a − b)² = a² − 2ab + b² to find 29².
- 27.If a + b = 5 and ab = 6, what is a² + b²?
- 28.Use a² − b² = (a + b)(a − b) to find 52² − 2².
- 29.Use a² − b² = (a + b)(a − b) to find 88² − 40².
- 30.Use (a − b)² = a² − 2ab + b² to find 86².
- 31.Use a² − b² = (a + b)(a − b) to find 63² − 40².
- 32.If a + b = 3 and ab = 2, what is a² + b²?
- 33.Use (a + b)² = a² + 2ab + b² to find 19².
- 34.Use (a + b)(a − b) = a² − b² to find 89 × 71.
- 35.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 36.If a + b = 10 and ab = 21, what is a² + b²?
- 37.Use (a − b)² = a² − 2ab + b² to find 81².
- 38.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 39.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 40.Use (a − b)² = a² − 2ab + b² to find 23².
Answer key
- 400
- 1521
- 4489
- 11236
- 49
- 5184
- 3481
- 8649
- 100
- 896
- 7569
- 168
- 3596
- 1764
- 3243
- 6724
- 25
- 221
- 576
- 45
- 441
- 3575
- 399
- 136
- 7225
- 841
- 13
- 2700
- 6144
- 7396
- 2369
- 5
- 361
- 6319
- 1551
- 58
- 6561
- 6336
- 2484
- 529
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