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 35².
- 2.Use (a + b)(a − b) = a² − b² to find 96 × 84.
- 3.Use (a − b)² = a² − 2ab + b² to find 87².
- 4.Use (a + b)² = a² + 2ab + b² to find 74².
- 5.Use a² − b² = (a + b)(a − b) to find 20² − 16².
- 6.Use (a + b)² = a² + 2ab + b² to find 108².
- 7.Use (a + b)(a − b) = a² − b² to find 108 × 92.
- 8.Use (a + b)(a − b) = a² − b² to find 103 × 97.
- 9.Use (a + b)(a − b) = a² − b² to find 51 × 49.
- 10.Use (a + b)² = a² + 2ab + b² to find 18².
- 11.If a + b = 12 and ab = 32, what is a² + b²?
- 12.Find the value of x² + 2xy + y² when x = 4 and y = 2.
- 13.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 14.Use a² − b² = (a + b)(a − b) to find 90² − 36².
- 15.Use (a − b)² = a² − 2ab + b² to find 81².
- 16.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 17.Use (a − b)² = a² − 2ab + b² to find 26².
- 18.Use (a − b)² = a² − 2ab + b² to find 18².
- 19.Use a² − b² = (a + b)(a − b) to find 82² − 66².
- 20.If a + b = 14 and ab = 40, what is a² + b²?
- 21.Use (a + b)² = a² + 2ab + b² to find 59².
- 22.Use (a + b)² = a² + 2ab + b² to find 79².
- 23.If a − b = 4 and ab = 21, what is a² + b²?
- 24.Use (a − b)² = a² − 2ab + b² to find 66².
- 25.Use (a + b)² = a² + 2ab + b² to find 32².
- 26.Use a² − b² = (a + b)(a − b) to find 41² − 38².
- 27.Use (a + b)² = a² + 2ab + b² to find 37².
- 28.Use (a − b)² = a² − 2ab + b² to find 61².
- 29.Use (a + b)² = a² + 2ab + b² to find 29².
- 30.If a − b = 1 and ab = 2, what is a² + b²?
- 31.Use (a − b)² = a² − 2ab + b² to find 74².
- 32.Use (a − b)² = a² − 2ab + b² to find 42².
- 33.Use a² − b² = (a + b)(a − b) to find 52² − 49².
- 34.Use (a + b)(a − b) = a² − b² to find 73 × 67.
- 35.Use a² − b² = (a + b)(a − b) to find 74² − 46².
- 36.Use (a + b)(a − b) = a² − b² to find 107 × 93.
- 37.Use (a − b)² = a² − 2ab + b² to find 85².
- 38.Use (a + b)² = a² + 2ab + b² to find 85².
- 39.Find the value of x² − y² when x = 9 and y = 4.
- 40.If a − b = 3 and ab = 10, what is a² + b²?
Answer key
- 1225
- 8064
- 7569
- 5476
- 144
- 11664
- 9936
- 9991
- 2499
- 324
- 80
- 36
- 25
- 6804
- 6561
- 3591
- 676
- 324
- 2368
- 116
- 3481
- 6241
- 58
- 4356
- 1024
- 237
- 1369
- 3721
- 841
- 5
- 5476
- 1764
- 303
- 4891
- 3360
- 9951
- 7225
- 7225
- 65
- 29
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