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 62 × 58.
- 2.Use (a + b)² = a² + 2ab + b² to find 24².
- 3.Use (a + b)(a − b) = a² − b² to find 46 × 34.
- 4.Use (a + b)² = a² + 2ab + b² to find 104².
- 5.If a + b = 12 and ab = 20, what is a² + b²?
- 6.Find the value of x² + 2xy + y² when x = 4 and y = 1.
- 7.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 8.Use (a + b)² = a² + 2ab + b² to find 31².
- 9.Use (a + b)(a − b) = a² − b² to find 74 × 66.
- 10.Use (a + b)(a − b) = a² − b² to find 87 × 73.
- 11.Use (a − b)² = a² − 2ab + b² to find 75².
- 12.If a + b = 10 and ab = 21, what is a² + b²?
- 13.Use a² − b² = (a + b)(a − b) to find 59² − 48².
- 14.Use (a + b)(a − b) = a² − b² to find 73 × 67.
- 15.Use (a + b)(a − b) = a² − b² to find 85 × 75.
- 16.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 17.Use (a + b)² = a² + 2ab + b² to find 99².
- 18.Use (a − b)² = a² − 2ab + b² to find 84².
- 19.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 20.Use (a − b)² = a² − 2ab + b² to find 62².
- 21.Use (a + b)² = a² + 2ab + b² to find 102².
- 22.If a − b = 5 and ab = 6, what is a² + b²?
- 23.Use (a + b)(a − b) = a² − b² to find 108 × 92.
- 24.Use (a + b)² = a² + 2ab + b² to find 21².
- 25.Find the value of x² − 2xy + y² when x = 7 and y = 5.
- 26.Use (a + b)² = a² + 2ab + b² to find 83².
- 27.Use (a + b)² = a² + 2ab + b² to find 51².
- 28.If a − b = 1 and ab = 6, what is a² + b²?
- 29.Use (a − b)² = a² − 2ab + b² to find 76².
- 30.Find the value of x² − 2xy + y² when x = 8 and y = 4.
- 31.Use (a − b)² = a² − 2ab + b² to find 83².
- 32.Use (a − b)² = a² − 2ab + b² to find 56².
- 33.Use (a + b)² = a² + 2ab + b² to find 22².
- 34.If a − b = 4 and ab = 5, what is a² + b²?
- 35.Use a² − b² = (a + b)(a − b) to find 29² − 28².
- 36.If a + b = 8 and ab = 15, what is a² + b²?
- 37.Use (a − b)² = a² − 2ab + b² to find 12².
- 38.Use (a + b)(a − b) = a² − b² to find 109 × 91.
- 39.If a + b = 3 and ab = 2, what is a² + b²?
- 40.Use (a − b)² = a² − 2ab + b² to find 78².
Answer key
- 3596
- 576
- 1564
- 10816
- 104
- 25
- 1591
- 961
- 4884
- 6351
- 5625
- 58
- 1177
- 4891
- 6375
- 3591
- 9801
- 7056
- 1551
- 3844
- 10404
- 37
- 9936
- 441
- 4
- 6889
- 2601
- 13
- 5776
- 16
- 6889
- 3136
- 484
- 26
- 57
- 34
- 144
- 9919
- 5
- 6084
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