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 = 11 and y = 8.
- 2.Use a² − b² = (a + b)(a − b) to find 84² − 21².
- 3.Use a² − b² = (a + b)(a − b) to find 62² − 53².
- 4.Find the value of x² + 2xy + y² when x = 12 and y = 7.
- 5.If a − b = 2 and ab = 8, what is a² + b²?
- 6.Use (a − b)² = a² − 2ab + b² to find 31².
- 7.Use (a − b)² = a² − 2ab + b² to find 29².
- 8.Use a² − b² = (a + b)(a − b) to find 56² − 44².
- 9.Use a² − b² = (a + b)(a − b) to find 50² − 30².
- 10.Use a² − b² = (a + b)(a − b) to find 21² − 19².
- 11.Use (a + b)(a − b) = a² − b² to find 81 × 79.
- 12.Use (a − b)² = a² − 2ab + b² to find 22².
- 13.Find the value of x² − 2xy + y² when x = 13 and y = 12.
- 14.Use a² − b² = (a + b)(a − b) to find 60² − 15².
- 15.Use (a + b)² = a² + 2ab + b² to find 98².
- 16.Use (a + b)² = a² + 2ab + b² to find 79².
- 17.Use (a + b)² = a² + 2ab + b² to find 95².
- 18.Use (a + b)² = a² + 2ab + b² to find 62².
- 19.Find the value of x² − 2xy + y² when x = 9 and y = 5.
- 20.Use (a + b)² = a² + 2ab + b² to find 13².
- 21.Use (a + b)² = a² + 2ab + b² to find 44².
- 22.Find the value of x² − y² when x = 3 and y = 1.
- 23.Use (a + b)² = a² + 2ab + b² to find 61².
- 24.Use (a − b)² = a² − 2ab + b² to find 12².
- 25.Use a² − b² = (a + b)(a − b) to find 67² − 54².
- 26.Use (a − b)² = a² − 2ab + b² to find 27².
- 27.If a + b = 5 and ab = 6, what is a² + b²?
- 28.Find the value of x² − y² when x = 10 and y = 5.
- 29.If a + b = 9 and ab = 20, what is a² + b²?
- 30.Use (a + b)² = a² + 2ab + b² to find 57².
- 31.Use a² − b² = (a + b)(a − b) to find 26² − 7².
- 32.Find the value of x² + 2xy + y² when x = 3 and y = 1.
- 33.Use (a − b)² = a² − 2ab + b² to find 62².
- 34.Use (a + b)(a − b) = a² − b² to find 39 × 21.
- 35.Find the value of x² − y² when x = 13 and y = 2.
- 36.Use a² − b² = (a + b)(a − b) to find 82² − 73².
- 37.Use a² − b² = (a + b)(a − b) to find 86² − 12².
- 38.If a − b = 5 and ab = 50, what is a² + b²?
- 39.Use (a + b)(a − b) = a² − b² to find 55 × 45.
- 40.If a + b = 11 and ab = 30, what is a² + b²?
Answer key
- 361
- 6615
- 1035
- 361
- 20
- 961
- 841
- 1200
- 1600
- 80
- 6399
- 484
- 1
- 3375
- 9604
- 6241
- 9025
- 3844
- 16
- 169
- 1936
- 8
- 3721
- 144
- 1573
- 729
- 13
- 75
- 41
- 3249
- 627
- 16
- 3844
- 819
- 165
- 1395
- 7252
- 125
- 2475
- 61
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