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 = 9 and y = 7.
- 2.If a − b = 5 and ab = 36, what is a² + b²?
- 3.Use a² − b² = (a + b)(a − b) to find 96² − 77².
- 4.Find the value of x² + 2xy + y² when x = 10 and y = 2.
- 5.Find the value of x² + 2xy + y² when x = 13 and y = 5.
- 6.Use (a − b)² = a² − 2ab + b² to find 11².
- 7.Use a² − b² = (a + b)(a − b) to find 39² − 21².
- 8.Use (a + b)(a − b) = a² − b² to find 82 × 78.
- 9.Find the value of x² + 2xy + y² when x = 15 and y = 1.
- 10.Find the value of x² − 2xy + y² when x = 3 and y = 2.
- 11.If a + b = 14 and ab = 33, what is a² + b²?
- 12.Use a² − b² = (a + b)(a − b) to find 82² − 4².
- 13.Use a² − b² = (a + b)(a − b) to find 76² − 20².
- 14.Use (a + b)² = a² + 2ab + b² to find 107².
- 15.Use a² − b² = (a + b)(a − b) to find 42² − 21².
- 16.Use (a + b)² = a² + 2ab + b² to find 34².
- 17.Use (a − b)² = a² − 2ab + b² to find 53².
- 18.Use (a + b)² = a² + 2ab + b² to find 93².
- 19.If a + b = 12 and ab = 32, what is a² + b²?
- 20.Use (a + b)(a − b) = a² − b² to find 84 × 76.
- 21.Use a² − b² = (a + b)(a − b) to find 70² − 56².
- 22.Use (a − b)² = a² − 2ab + b² to find 69².
- 23.Use (a + b)² = a² + 2ab + b² to find 95².
- 24.Use (a − b)² = a² − 2ab + b² to find 99².
- 25.Use (a + b)(a − b) = a² − b² to find 94 × 86.
- 26.Use (a + b)(a − b) = a² − b² to find 69 × 51.
- 27.If a + b = 10 and ab = 21, what is a² + b²?
- 28.If a − b = 1 and ab = 2, what is a² + b²?
- 29.Use (a − b)² = a² − 2ab + b² to find 75².
- 30.Use (a + b)² = a² + 2ab + b² to find 69².
- 31.If a + b = 16 and ab = 60, what is a² + b²?
- 32.Find the value of x² − y² when x = 11 and y = 5.
- 33.Use (a + b)(a − b) = a² − b² to find 39 × 21.
- 34.Find the value of x² − 2xy + y² when x = 4 and y = 1.
- 35.Use (a + b)² = a² + 2ab + b² to find 11².
- 36.Use a² − b² = (a + b)(a − b) to find 30² − 24².
- 37.If a + b = 12 and ab = 11, what is a² + b²?
- 38.If a + b = 15 and ab = 56, what is a² + b²?
- 39.Use (a + b)(a − b) = a² − b² to find 87 × 73.
- 40.Use a² − b² = (a + b)(a − b) to find 85² − 35².
Answer key
- 4
- 97
- 3287
- 144
- 324
- 121
- 1080
- 6396
- 256
- 1
- 130
- 6708
- 5376
- 11449
- 1323
- 1156
- 2809
- 8649
- 80
- 6384
- 1764
- 4761
- 9025
- 9801
- 8084
- 3519
- 58
- 5
- 5625
- 4761
- 136
- 96
- 819
- 9
- 121
- 324
- 122
- 113
- 6351
- 6000
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