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.If a − b = 10 and ab = 11, what is a² + b²?
- 2.Find the value of x² + 2xy + y² when x = 4 and y = 1.
- 3.Use (a − b)² = a² − 2ab + b² to find 78².
- 4.Find the value of x² − y² when x = 9 and y = 6.
- 5.If a − b = 1 and ab = 42, what is a² + b²?
- 6.Find the value of x² − 2xy + y² when x = 14 and y = 10.
- 7.Use (a + b)² = a² + 2ab + b² to find 85².
- 8.Find the value of x² − y² when x = 12 and y = 2.
- 9.Find the value of x² + 2xy + y² when x = 7 and y = 1.
- 10.Use (a − b)² = a² − 2ab + b² to find 96².
- 11.Find the value of x² − y² when x = 8 and y = 1.
- 12.Use (a − b)² = a² − 2ab + b² to find 79².
- 13.If a − b = 9 and ab = 10, what is a² + b²?
- 14.If a − b = 3 and ab = 10, what is a² + b²?
- 15.If a + b = 17 and ab = 60, what is a² + b²?
- 16.Use (a + b)² = a² + 2ab + b² to find 76².
- 17.Use a² − b² = (a + b)(a − b) to find 63² − 60².
- 18.Find the value of x² + 2xy + y² when x = 11 and y = 8.
- 19.Use a² − b² = (a + b)(a − b) to find 52² − 37².
- 20.Find the value of x² + 2xy + y² when x = 4 and y = 2.
- 21.Use a² − b² = (a + b)(a − b) to find 84² − 45².
- 22.Use (a − b)² = a² − 2ab + b² to find 39².
- 23.Use (a + b)(a − b) = a² − b² to find 69 × 51.
- 24.Use (a − b)² = a² − 2ab + b² to find 21².
- 25.Use (a − b)² = a² − 2ab + b² to find 34².
- 26.Find the value of x² + 2xy + y² when x = 8 and y = 4.
- 27.If a + b = 19 and ab = 84, what is a² + b²?
- 28.Use (a − b)² = a² − 2ab + b² to find 22².
- 29.Use (a + b)² = a² + 2ab + b² to find 102².
- 30.Use (a − b)² = a² − 2ab + b² to find 45².
- 31.Use (a + b)² = a² + 2ab + b² to find 16².
- 32.If a − b = 3 and ab = 70, what is a² + b²?
- 33.If a − b = 6 and ab = 7, what is a² + b²?
- 34.Find the value of x² + 2xy + y² when x = 11 and y = 4.
- 35.Use (a − b)² = a² − 2ab + b² to find 85².
- 36.Find the value of x² − y² when x = 4 and y = 2.
- 37.Use (a − b)² = a² − 2ab + b² to find 83².
- 38.Use (a + b)² = a² + 2ab + b² to find 53².
- 39.Use a² − b² = (a + b)(a − b) to find 73² − 56².
- 40.Find the value of x² − y² when x = 13 and y = 5.
Answer key
- 122
- 25
- 6084
- 45
- 85
- 16
- 7225
- 140
- 64
- 9216
- 63
- 6241
- 101
- 29
- 169
- 5776
- 369
- 361
- 1335
- 36
- 5031
- 1521
- 3519
- 441
- 1156
- 144
- 193
- 484
- 10404
- 2025
- 256
- 149
- 50
- 225
- 7225
- 12
- 6889
- 2809
- 2193
- 144
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