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 = 12 and y = 4.
- 2.Find the value of x² − 2xy + y² when x = 3 and y = 1.
- 3.Use (a − b)² = a² − 2ab + b² to find 15².
- 4.Find the value of x² − 2xy + y² when x = 6 and y = 1.
- 5.Use a² − b² = (a + b)(a − b) to find 37² − 3².
- 6.Use (a − b)² = a² − 2ab + b² to find 65².
- 7.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 8.Use (a + b)(a − b) = a² − b² to find 91 × 89.
- 9.Use (a − b)² = a² − 2ab + b² to find 89².
- 10.Use (a − b)² = a² − 2ab + b² to find 64².
- 11.Use (a + b)² = a² + 2ab + b² to find 79².
- 12.Find the value of x² − y² when x = 4 and y = 1.
- 13.Use (a + b)² = a² + 2ab + b² to find 64².
- 14.Use (a + b)² = a² + 2ab + b² to find 73².
- 15.Use (a − b)² = a² − 2ab + b² to find 69².
- 16.Use a² − b² = (a + b)(a − b) to find 28² − 27².
- 17.Use a² − b² = (a + b)(a − b) to find 27² − 16².
- 18.Use (a − b)² = a² − 2ab + b² to find 21².
- 19.Use (a + b)² = a² + 2ab + b² to find 62².
- 20.Use (a + b)(a − b) = a² − b² to find 52 × 48.
- 21.Use (a + b)(a − b) = a² − b² to find 58 × 42.
- 22.Use a² − b² = (a + b)(a − b) to find 69² − 5².
- 23.Use (a + b)(a − b) = a² − b² to find 33 × 27.
- 24.If a + b = 5 and ab = 6, what is a² + b²?
- 25.Use (a + b)(a − b) = a² − b² to find 28 × 12.
- 26.Find the value of x² + 2xy + y² when x = 7 and y = 2.
- 27.Find the value of x² + 2xy + y² when x = 12 and y = 6.
- 28.Use (a + b)(a − b) = a² − b² to find 104 × 96.
- 29.Use (a + b)(a − b) = a² − b² to find 89 × 71.
- 30.Use (a + b)² = a² + 2ab + b² to find 52².
- 31.Use (a − b)² = a² − 2ab + b² to find 97².
- 32.If a + b = 6 and ab = 8, what is a² + b²?
- 33.Find the value of x² − 2xy + y² when x = 12 and y = 2.
- 34.Use (a + b)(a − b) = a² − b² to find 108 × 92.
- 35.Use (a − b)² = a² − 2ab + b² to find 57².
- 36.If a + b = 8 and ab = 12, what is a² + b²?
- 37.Use a² − b² = (a + b)(a − b) to find 98² − 14².
- 38.Use (a + b)(a − b) = a² − b² to find 37 × 23.
- 39.If a + b = 7 and ab = 12, what is a² + b²?
- 40.Use (a + b)(a − b) = a² − b² to find 68 × 52.
Answer key
- 64
- 4
- 225
- 25
- 1360
- 4225
- 399
- 8099
- 7921
- 4096
- 6241
- 15
- 4096
- 5329
- 4761
- 55
- 473
- 441
- 3844
- 2496
- 2436
- 4736
- 891
- 13
- 336
- 81
- 324
- 9984
- 6319
- 2704
- 9409
- 20
- 100
- 9936
- 3249
- 40
- 9408
- 851
- 25
- 3536
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