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 = 15 and y = 7.
- 2.If a − b = 5 and ab = 24, what is a² + b²?
- 3.Use a² − b² = (a + b)(a − b) to find 84² − 57².
- 4.Use (a − b)² = a² − 2ab + b² to find 95².
- 5.Use (a + b)² = a² + 2ab + b² to find 37².
- 6.Use (a − b)² = a² − 2ab + b² to find 48².
- 7.Use (a + b)² = a² + 2ab + b² to find 103².
- 8.Use a² − b² = (a + b)(a − b) to find 56² − 37².
- 9.Use (a + b)² = a² + 2ab + b² to find 102².
- 10.If a − b = 1 and ab = 110, what is a² + b²?
- 11.Find the value of x² − y² when x = 13 and y = 3.
- 12.If a + b = 16 and ab = 55, what is a² + b²?
- 13.Use (a − b)² = a² − 2ab + b² to find 35².
- 14.Use (a + b)(a − b) = a² − b² to find 79 × 61.
- 15.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 16.Use (a − b)² = a² − 2ab + b² to find 93².
- 17.Find the value of x² − y² when x = 3 and y = 2.
- 18.Use (a + b)² = a² + 2ab + b² to find 89².
- 19.Use (a − b)² = a² − 2ab + b² to find 38².
- 20.If a + b = 15 and ab = 50, what is a² + b²?
- 21.If a − b = 6 and ab = 27, what is a² + b²?
- 22.Find the value of x² − 2xy + y² when x = 9 and y = 5.
- 23.If a − b = 4 and ab = 60, what is a² + b²?
- 24.Find the value of x² + 2xy + y² when x = 5 and y = 1.
- 25.Use a² − b² = (a + b)(a − b) to find 25² − 23².
- 26.Use (a + b)(a − b) = a² − b² to find 68 × 52.
- 27.Use (a + b)² = a² + 2ab + b² to find 73².
- 28.Use (a − b)² = a² − 2ab + b² to find 31².
- 29.If a + b = 17 and ab = 66, what is a² + b²?
- 30.Find the value of x² − 2xy + y² when x = 5 and y = 1.
- 31.Use (a + b)² = a² + 2ab + b² to find 51².
- 32.If a + b = 5 and ab = 4, what is a² + b²?
- 33.Use (a + b)(a − b) = a² − b² to find 94 × 86.
- 34.Use (a + b)(a − b) = a² − b² to find 31 × 29.
- 35.If a − b = 3 and ab = 28, what is a² + b²?
- 36.Use (a + b)² = a² + 2ab + b² to find 34².
- 37.If a + b = 12 and ab = 35, what is a² + b²?
- 38.Use (a − b)² = a² − 2ab + b² to find 87².
- 39.Use (a − b)² = a² − 2ab + b² to find 34².
- 40.Use a² − b² = (a + b)(a − b) to find 92² − 85².
Answer key
- 64
- 73
- 3807
- 9025
- 1369
- 2304
- 10609
- 1767
- 10404
- 221
- 160
- 146
- 1225
- 4819
- 384
- 8649
- 5
- 7921
- 1444
- 125
- 90
- 16
- 136
- 36
- 96
- 3536
- 5329
- 961
- 157
- 16
- 2601
- 17
- 8084
- 899
- 65
- 1156
- 74
- 7569
- 1156
- 1239
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