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)² = a² − 2ab + b² to find 26².
- 2.Use (a − b)² = a² − 2ab + b² to find 47².
- 3.If a − b = 6 and ab = 16, what is a² + b²?
- 4.If a + b = 14 and ab = 40, what is a² + b²?
- 5.Use (a + b)² = a² + 2ab + b² to find 93².
- 6.Use a² − b² = (a + b)(a − b) to find 91² − 65².
- 7.Use (a + b)² = a² + 2ab + b² to find 39².
- 8.If a + b = 12 and ab = 32, what is a² + b²?
- 9.Use (a − b)² = a² − 2ab + b² to find 41².
- 10.Use (a + b)(a − b) = a² − b² to find 46 × 34.
- 11.Use (a + b)² = a² + 2ab + b² to find 101².
- 12.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 13.If a + b = 5 and ab = 6, what is a² + b²?
- 14.If a + b = 4 and ab = 3, what is a² + b²?
- 15.Use (a + b)² = a² + 2ab + b² to find 51².
- 16.Use a² − b² = (a + b)(a − b) to find 91² − 84².
- 17.Use (a − b)² = a² − 2ab + b² to find 19².
- 18.Find the value of x² − y² when x = 15 and y = 10.
- 19.Use a² − b² = (a + b)(a − b) to find 77² − 41².
- 20.Use (a + b)² = a² + 2ab + b² to find 61².
- 21.Use (a + b)(a − b) = a² − b² to find 79 × 61.
- 22.Use a² − b² = (a + b)(a − b) to find 43² − 1².
- 23.Use (a + b)² = a² + 2ab + b² to find 54².
- 24.Use (a + b)(a − b) = a² − b² to find 26 × 14.
- 25.Find the value of x² − y² when x = 9 and y = 3.
- 26.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 27.Find the value of x² − 2xy + y² when x = 9 and y = 6.
- 28.Use (a − b)² = a² − 2ab + b² to find 55².
- 29.Use (a + b)(a − b) = a² − b² to find 107 × 93.
- 30.Use (a + b)² = a² + 2ab + b² to find 18².
- 31.If a + b = 21 and ab = 108, what is a² + b²?
- 32.Use (a + b)(a − b) = a² − b² to find 48 × 32.
- 33.If a + b = 9 and ab = 20, what is a² + b²?
- 34.Use (a − b)² = a² − 2ab + b² to find 15².
- 35.If a + b = 18 and ab = 72, what is a² + b²?
- 36.Use (a − b)² = a² − 2ab + b² to find 45².
- 37.Use a² − b² = (a + b)(a − b) to find 53² − 8².
- 38.If a − b = 1 and ab = 2, what is a² + b²?
- 39.Use (a + b)² = a² + 2ab + b² to find 36².
- 40.Use (a + b)² = a² + 2ab + b² to find 73².
Answer key
- 676
- 2209
- 68
- 116
- 8649
- 4056
- 1521
- 80
- 1681
- 1564
- 10201
- 391
- 13
- 10
- 2601
- 1225
- 361
- 125
- 4248
- 3721
- 4819
- 1848
- 2916
- 364
- 72
- 6336
- 9
- 3025
- 9951
- 324
- 225
- 1536
- 41
- 225
- 180
- 2025
- 2745
- 5
- 1296
- 5329
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