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 22 × 18.
- 2.Use (a + b)(a − b) = a² − b² to find 61 × 59.
- 3.Use (a − b)² = a² − 2ab + b² to find 62².
- 4.Use a² − b² = (a + b)(a − b) to find 78² − 6².
- 5.Use (a + b)² = a² + 2ab + b² to find 75².
- 6.Use (a − b)² = a² − 2ab + b² to find 87².
- 7.Use (a − b)² = a² − 2ab + b² to find 16².
- 8.Use (a + b)² = a² + 2ab + b² to find 93².
- 9.Use a² − b² = (a + b)(a − b) to find 31² − 11².
- 10.Use a² − b² = (a + b)(a − b) to find 69² − 12².
- 11.Use (a − b)² = a² − 2ab + b² to find 31².
- 12.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 13.If a − b = 5 and ab = 14, what is a² + b²?
- 14.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 15.Use (a + b)(a − b) = a² − b² to find 57 × 43.
- 16.Use (a − b)² = a² − 2ab + b² to find 44².
- 17.Use (a − b)² = a² − 2ab + b² to find 22².
- 18.Use (a + b)(a − b) = a² − b² to find 56 × 44.
- 19.If a + b = 10 and ab = 21, what is a² + b²?
- 20.Use a² − b² = (a + b)(a − b) to find 98² − 52².
- 21.Use a² − b² = (a + b)(a − b) to find 49² − 31².
- 22.Use a² − b² = (a + b)(a − b) to find 83² − 28².
- 23.Use (a − b)² = a² − 2ab + b² to find 37².
- 24.If a + b = 14 and ab = 48, what is a² + b²?
- 25.Use a² − b² = (a + b)(a − b) to find 95² − 43².
- 26.Find the value of x² − y² when x = 3 and y = 1.
- 27.Use (a − b)² = a² − 2ab + b² to find 67².
- 28.Use (a + b)² = a² + 2ab + b² to find 89².
- 29.Use (a + b)² = a² + 2ab + b² to find 59².
- 30.Use (a + b)² = a² + 2ab + b² to find 61².
- 31.If a − b = 1 and ab = 20, what is a² + b²?
- 32.Use (a + b)(a − b) = a² − b² to find 97 × 83.
- 33.Use (a + b)(a − b) = a² − b² to find 84 × 76.
- 34.Find the value of x² − y² when x = 6 and y = 4.
- 35.Use (a + b)² = a² + 2ab + b² to find 62².
- 36.If a − b = 1 and ab = 30, what is a² + b²?
- 37.If a + b = 14 and ab = 40, what is a² + b²?
- 38.Find the value of x² − 2xy + y² when x = 14 and y = 1.
- 39.Use (a − b)² = a² − 2ab + b² to find 13².
- 40.Find the value of x² − 2xy + y² when x = 6 and y = 1.
Answer key
- 396
- 3599
- 3844
- 6048
- 5625
- 7569
- 256
- 8649
- 840
- 4617
- 961
- 3591
- 53
- 399
- 2451
- 1936
- 484
- 2464
- 58
- 6900
- 1440
- 6105
- 1369
- 100
- 7176
- 8
- 4489
- 7921
- 3481
- 3721
- 41
- 8051
- 6384
- 20
- 3844
- 61
- 116
- 169
- 169
- 25
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