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 84 × 76.
- 2.Use (a + b)² = a² + 2ab + b² to find 19².
- 3.Use (a − b)² = a² − 2ab + b² to find 97².
- 4.Use (a + b)² = a² + 2ab + b² to find 23².
- 5.Use a² − b² = (a + b)(a − b) to find 84² − 45².
- 6.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 7.If a − b = 3 and ab = 108, what is a² + b²?
- 8.Use (a − b)² = a² − 2ab + b² to find 25².
- 9.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 10.Use a² − b² = (a + b)(a − b) to find 86² − 2².
- 11.Use (a − b)² = a² − 2ab + b² to find 35².
- 12.Use (a + b)² = a² + 2ab + b² to find 14².
- 13.Use (a + b)² = a² + 2ab + b² to find 94².
- 14.Use (a + b)(a − b) = a² − b² to find 46 × 34.
- 15.If a + b = 3 and ab = 2, what is a² + b²?
- 16.Use (a − b)² = a² − 2ab + b² to find 41².
- 17.Use (a + b)² = a² + 2ab + b² to find 49².
- 18.Find the value of x² − y² when x = 4 and y = 1.
- 19.Use (a − b)² = a² − 2ab + b² to find 67².
- 20.Use (a + b)(a − b) = a² − b² to find 32 × 28.
- 21.Use a² − b² = (a + b)(a − b) to find 62² − 24².
- 22.Use (a − b)² = a² − 2ab + b² to find 95².
- 23.Use (a − b)² = a² − 2ab + b² to find 15².
- 24.If a + b = 10 and ab = 16, what is a² + b²?
- 25.Use (a − b)² = a² − 2ab + b² to find 49².
- 26.Find the value of x² − 2xy + y² when x = 6 and y = 4.
- 27.Use (a + b)² = a² + 2ab + b² to find 46².
- 28.If a − b = 10 and ab = 11, what is a² + b²?
- 29.If a − b = 2 and ab = 120, what is a² + b²?
- 30.Use a² − b² = (a + b)(a − b) to find 26² − 14².
- 31.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 32.Use (a + b)(a − b) = a² − b² to find 106 × 94.
- 33.If a + b = 11 and ab = 30, what is a² + b²?
- 34.Use a² − b² = (a + b)(a − b) to find 81² − 68².
- 35.Use (a + b)(a − b) = a² − b² to find 38 × 22.
- 36.Use (a + b)(a − b) = a² − b² to find 81 × 79.
- 37.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 38.Use (a − b)² = a² − 2ab + b² to find 36².
- 39.Use (a + b)(a − b) = a² − b² to find 27 × 13.
- 40.Use (a + b)² = a² + 2ab + b² to find 72².
Answer key
- 6384
- 361
- 9409
- 529
- 5031
- 3591
- 225
- 625
- 6336
- 7392
- 1225
- 196
- 8836
- 1564
- 5
- 1681
- 2401
- 15
- 4489
- 896
- 3268
- 9025
- 225
- 68
- 2401
- 4
- 2116
- 122
- 244
- 480
- 875
- 9964
- 61
- 1937
- 836
- 6399
- 1551
- 1296
- 351
- 5184
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