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 = 13 and y = 2.
- 2.If a + b = 15 and ab = 56, what is a² + b²?
- 3.Use (a + b)² = a² + 2ab + b² to find 23².
- 4.Use a² − b² = (a + b)(a − b) to find 55² − 17².
- 5.Use (a − b)² = a² − 2ab + b² to find 23².
- 6.Use (a − b)² = a² − 2ab + b² to find 79².
- 7.Find the value of x² + 2xy + y² when x = 3 and y = 1.
- 8.Use (a − b)² = a² − 2ab + b² to find 96².
- 9.Use (a − b)² = a² − 2ab + b² to find 52².
- 10.Use (a + b)² = a² + 2ab + b² to find 16².
- 11.Use (a + b)² = a² + 2ab + b² to find 63².
- 12.Find the value of x² − 2xy + y² when x = 10 and y = 7.
- 13.Use (a + b)² = a² + 2ab + b² to find 56².
- 14.Use a² − b² = (a + b)(a − b) to find 89² − 28².
- 15.If a + b = 9 and ab = 20, what is a² + b²?
- 16.Use (a + b)(a − b) = a² − b² to find 83 × 77.
- 17.If a + b = 5 and ab = 6, what is a² + b²?
- 18.Use a² − b² = (a + b)(a − b) to find 47² − 20².
- 19.Find the value of x² − 2xy + y² when x = 12 and y = 8.
- 20.Use a² − b² = (a + b)(a − b) to find 89² − 51².
- 21.Use a² − b² = (a + b)(a − b) to find 79² − 16².
- 22.Use (a + b)² = a² + 2ab + b² to find 82².
- 23.If a − b = 2 and ab = 63, what is a² + b²?
- 24.If a − b = 1 and ab = 6, what is a² + b²?
- 25.Find the value of x² + 2xy + y² when x = 6 and y = 1.
- 26.Use a² − b² = (a + b)(a − b) to find 34² − 5².
- 27.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 28.Use (a − b)² = a² − 2ab + b² to find 69².
- 29.Use (a + b)(a − b) = a² − b² to find 59 × 41.
- 30.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 31.Use (a + b)(a − b) = a² − b² to find 81 × 79.
- 32.Use (a + b)² = a² + 2ab + b² to find 73².
- 33.Use (a + b)(a − b) = a² − b² to find 99 × 81.
- 34.Use (a − b)² = a² − 2ab + b² to find 83².
- 35.If a + b = 5 and ab = 4, what is a² + b²?
- 36.Use (a − b)² = a² − 2ab + b² to find 33².
- 37.If a − b = 3 and ab = 4, what is a² + b²?
- 38.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 39.Use a² − b² = (a + b)(a − b) to find 32² − 6².
- 40.Use a² − b² = (a + b)(a − b) to find 61² − 4².
Answer key
- 121
- 113
- 529
- 2736
- 529
- 6241
- 16
- 9216
- 2704
- 256
- 3969
- 9
- 3136
- 7137
- 41
- 6391
- 13
- 1809
- 16
- 5320
- 5985
- 6724
- 130
- 13
- 49
- 1131
- 1551
- 4761
- 2419
- 384
- 6399
- 5329
- 8019
- 6889
- 17
- 1089
- 17
- 8091
- 988
- 3705
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