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 = 5 and ab = 6, what is a² + b²?
- 2.Find the value of x² − y² when x = 4 and y = 3.
- 3.Use a² − b² = (a + b)(a − b) to find 99² − 85².
- 4.Use (a + b)² = a² + 2ab + b² to find 106².
- 5.Use (a − b)² = a² − 2ab + b² to find 49².
- 6.Use (a − b)² = a² − 2ab + b² to find 37².
- 7.Use (a + b)² = a² + 2ab + b² to find 13².
- 8.Use (a + b)(a − b) = a² − b² to find 58 × 42.
- 9.Use (a − b)² = a² − 2ab + b² to find 78².
- 10.Find the value of x² − y² when x = 13 and y = 9.
- 11.Use (a − b)² = a² − 2ab + b² to find 54².
- 12.Use (a − b)² = a² − 2ab + b² to find 28².
- 13.If a + b = 17 and ab = 66, what is a² + b²?
- 14.Use a² − b² = (a + b)(a − b) to find 29² − 24².
- 15.If a + b = 18 and ab = 72, what is a² + b²?
- 16.Use (a − b)² = a² − 2ab + b² to find 52².
- 17.Use (a − b)² = a² − 2ab + b² to find 83².
- 18.If a + b = 15 and ab = 50, what is a² + b²?
- 19.If a + b = 3 and ab = 2, what is a² + b²?
- 20.Use (a + b)² = a² + 2ab + b² to find 22².
- 21.Use (a + b)² = a² + 2ab + b² to find 84².
- 22.Use (a − b)² = a² − 2ab + b² to find 76².
- 23.Use (a − b)² = a² − 2ab + b² to find 88².
- 24.Use a² − b² = (a + b)(a − b) to find 96² − 66².
- 25.Use (a + b)² = a² + 2ab + b² to find 69².
- 26.If a − b = 6 and ab = 16, what is a² + b²?
- 27.Use (a + b)² = a² + 2ab + b² to find 107².
- 28.Use (a + b)(a − b) = a² − b² to find 94 × 86.
- 29.Use (a + b)² = a² + 2ab + b² to find 14².
- 30.Use (a − b)² = a² − 2ab + b² to find 38².
- 31.Use (a + b)(a − b) = a² − b² to find 45 × 35.
- 32.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 33.Use a² − b² = (a + b)(a − b) to find 34² − 12².
- 34.Use (a + b)² = a² + 2ab + b² to find 98².
- 35.Use (a − b)² = a² − 2ab + b² to find 47².
- 36.Use (a − b)² = a² − 2ab + b² to find 13².
- 37.Find the value of x² + 2xy + y² when x = 4 and y = 1.
- 38.If a − b = 3 and ab = 54, what is a² + b²?
- 39.Use a² − b² = (a + b)(a − b) to find 26² − 17².
- 40.Use a² − b² = (a + b)(a − b) to find 42² − 26².
Answer key
- 37
- 7
- 2576
- 11236
- 2401
- 1369
- 169
- 2436
- 6084
- 88
- 2916
- 784
- 157
- 265
- 180
- 2704
- 6889
- 125
- 5
- 484
- 7056
- 5776
- 7744
- 4860
- 4761
- 68
- 11449
- 8084
- 196
- 1444
- 1575
- 399
- 1012
- 9604
- 2209
- 169
- 25
- 117
- 387
- 1088
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