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 = 3 and y = 2.
- 2.Find the value of x² − y² when x = 5 and y = 2.
- 3.Find the value of x² + 2xy + y² when x = 7 and y = 1.
- 4.Use a² − b² = (a + b)(a − b) to find 22² − 4².
- 5.Use (a + b)(a − b) = a² − b² to find 27 × 13.
- 6.Use (a + b)² = a² + 2ab + b² to find 109².
- 7.Use (a − b)² = a² − 2ab + b² to find 32².
- 8.Find the value of x² − y² when x = 3 and y = 1.
- 9.If a + b = 8 and ab = 15, what is a² + b²?
- 10.Use (a − b)² = a² − 2ab + b² to find 27².
- 11.Use a² − b² = (a + b)(a − b) to find 83² − 69².
- 12.Use (a − b)² = a² − 2ab + b² to find 55².
- 13.Use (a + b)² = a² + 2ab + b² to find 94².
- 14.Use (a + b)² = a² + 2ab + b² to find 16².
- 15.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 16.Use (a + b)² = a² + 2ab + b² to find 52².
- 17.Use a² − b² = (a + b)(a − b) to find 84² − 64².
- 18.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 19.Use a² − b² = (a + b)(a − b) to find 35² − 18².
- 20.Use (a + b)² = a² + 2ab + b² to find 53².
- 21.If a + b = 7 and ab = 10, what is a² + b²?
- 22.Use (a + b)² = a² + 2ab + b² to find 72².
- 23.Use (a + b)(a − b) = a² − b² to find 68 × 52.
- 24.If a + b = 9 and ab = 20, what is a² + b²?
- 25.If a + b = 3 and ab = 2, what is a² + b²?
- 26.Find the value of x² − y² when x = 10 and y = 2.
- 27.Use (a + b)² = a² + 2ab + b² to find 103².
- 28.If a + b = 6 and ab = 8, what is a² + b²?
- 29.Use (a − b)² = a² − 2ab + b² to find 15².
- 30.Use (a − b)² = a² − 2ab + b² to find 31².
- 31.If a + b = 12 and ab = 35, what is a² + b²?
- 32.Use (a − b)² = a² − 2ab + b² to find 89².
- 33.Use a² − b² = (a + b)(a − b) to find 78² − 37².
- 34.Use (a + b)(a − b) = a² − b² to find 96 × 84.
- 35.Use a² − b² = (a + b)(a − b) to find 74² − 46².
- 36.If a − b = 9 and ab = 10, what is a² + b²?
- 37.Use (a − b)² = a² − 2ab + b² to find 17².
- 38.Use (a + b)(a − b) = a² − b² to find 66 × 54.
- 39.Find the value of x² + 2xy + y² when x = 13 and y = 10.
- 40.If a + b = 15 and ab = 54, what is a² + b²?
Answer key
- 25
- 21
- 64
- 468
- 351
- 11881
- 1024
- 8
- 34
- 729
- 2128
- 3025
- 8836
- 256
- 3596
- 2704
- 2960
- 1591
- 901
- 2809
- 29
- 5184
- 3536
- 41
- 5
- 96
- 10609
- 20
- 225
- 961
- 74
- 7921
- 4715
- 8064
- 3360
- 101
- 289
- 3564
- 529
- 117
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