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 a² − b² = (a + b)(a − b) to find 93² − 27².
- 2.Use (a + b)² = a² + 2ab + b² to find 102².
- 3.Use (a − b)² = a² − 2ab + b² to find 31².
- 4.Use (a − b)² = a² − 2ab + b² to find 69².
- 5.Use (a + b)² = a² + 2ab + b² to find 16².
- 6.Use (a − b)² = a² − 2ab + b² to find 33².
- 7.Use (a − b)² = a² − 2ab + b² to find 41².
- 8.Use a² − b² = (a + b)(a − b) to find 20² − 4².
- 9.Find the value of x² − y² when x = 7 and y = 1.
- 10.Use a² − b² = (a + b)(a − b) to find 27² − 16².
- 11.Use (a − b)² = a² − 2ab + b² to find 27².
- 12.Use (a + b)² = a² + 2ab + b² to find 91².
- 13.Use a² − b² = (a + b)(a − b) to find 91² − 67².
- 14.If a + b = 12 and ab = 35, what is a² + b²?
- 15.Use a² − b² = (a + b)(a − b) to find 95² − 56².
- 16.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 17.Use a² − b² = (a + b)(a − b) to find 87² − 59².
- 18.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 19.Use (a − b)² = a² − 2ab + b² to find 83².
- 20.Find the value of x² + 2xy + y² when x = 7 and y = 5.
- 21.Use (a + b)² = a² + 2ab + b² to find 44².
- 22.Use (a + b)(a − b) = a² − b² to find 39 × 21.
- 23.If a − b = 2 and ab = 8, what is a² + b²?
- 24.Use (a + b)(a − b) = a² − b² to find 73 × 67.
- 25.If a − b = 1 and ab = 12, what is a² + b²?
- 26.Use (a + b)² = a² + 2ab + b² to find 39².
- 27.Use (a + b)(a − b) = a² − b² to find 42 × 38.
- 28.Use (a − b)² = a² − 2ab + b² to find 55².
- 29.Use (a + b)(a − b) = a² − b² to find 64 × 56.
- 30.If a + b = 18 and ab = 77, what is a² + b²?
- 31.If a + b = 5 and ab = 4, what is a² + b²?
- 32.Use (a − b)² = a² − 2ab + b² to find 36².
- 33.Find the value of x² − y² when x = 10 and y = 2.
- 34.Use (a − b)² = a² − 2ab + b² to find 89².
- 35.Find the value of x² − 2xy + y² when x = 11 and y = 9.
- 36.Use a² − b² = (a + b)(a − b) to find 70² − 27².
- 37.Use (a − b)² = a² − 2ab + b² to find 11².
- 38.If a + b = 6 and ab = 8, what is a² + b²?
- 39.If a + b = 7 and ab = 12, what is a² + b²?
- 40.Use (a − b)² = a² − 2ab + b² to find 22².
Answer key
- 7920
- 10404
- 961
- 4761
- 256
- 1089
- 1681
- 384
- 48
- 473
- 729
- 8281
- 3792
- 74
- 5889
- 3596
- 4088
- 6336
- 6889
- 144
- 1936
- 819
- 20
- 4891
- 25
- 1521
- 1596
- 3025
- 3584
- 170
- 17
- 1296
- 96
- 7921
- 4
- 4171
- 121
- 20
- 25
- 484
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