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.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 2.If a − b = 2 and ab = 3, what is a² + b²?
- 3.Use (a + b)² = a² + 2ab + b² to find 93².
- 4.If a + b = 3 and ab = 2, what is a² + b²?
- 5.Use (a − b)² = a² − 2ab + b² to find 62².
- 6.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 7.Use (a + b)² = a² + 2ab + b² to find 41².
- 8.Use (a − b)² = a² − 2ab + b² to find 14².
- 9.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 10.Use (a − b)² = a² − 2ab + b² to find 74².
- 11.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 12.Use (a − b)² = a² − 2ab + b² to find 68².
- 13.Use a² − b² = (a + b)(a − b) to find 66² − 14².
- 14.Use a² − b² = (a + b)(a − b) to find 71² − 1².
- 15.Use (a + b)(a − b) = a² − b² to find 67 × 53.
- 16.Find the value of x² − y² when x = 11 and y = 2.
- 17.Find the value of x² − 2xy + y² when x = 12 and y = 9.
- 18.Find the value of x² − y² when x = 12 and y = 6.
- 19.Use (a + b)² = a² + 2ab + b² to find 48².
- 20.If a + b = 12 and ab = 11, what is a² + b²?
- 21.Find the value of x² + 2xy + y² when x = 12 and y = 7.
- 22.Use (a + b)² = a² + 2ab + b² to find 102².
- 23.Use (a − b)² = a² − 2ab + b² to find 95².
- 24.Use (a + b)(a − b) = a² − b² to find 84 × 76.
- 25.Use a² − b² = (a + b)(a − b) to find 53² − 43².
- 26.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 27.Find the value of x² + 2xy + y² when x = 5 and y = 2.
- 28.Use (a + b)² = a² + 2ab + b² to find 104².
- 29.Use (a + b)² = a² + 2ab + b² to find 31².
- 30.Find the value of x² + 2xy + y² when x = 6 and y = 5.
- 31.Use a² − b² = (a + b)(a − b) to find 23² − 1².
- 32.Use (a − b)² = a² − 2ab + b² to find 61².
- 33.Use a² − b² = (a + b)(a − b) to find 22² − 1².
- 34.Find the value of x² − 2xy + y² when x = 9 and y = 5.
- 35.Use (a + b)² = a² + 2ab + b² to find 12².
- 36.Find the value of x² + 2xy + y² when x = 8 and y = 6.
- 37.Use (a + b)(a − b) = a² − b² to find 106 × 94.
- 38.Use (a − b)² = a² − 2ab + b² to find 88².
- 39.Use (a + b)² = a² + 2ab + b² to find 107².
- 40.Use a² − b² = (a + b)(a − b) to find 82² − 28².
Answer key
- 399
- 10
- 8649
- 5
- 3844
- 884
- 1681
- 196
- 384
- 5476
- 391
- 4624
- 4160
- 5040
- 3551
- 117
- 9
- 108
- 2304
- 122
- 361
- 10404
- 9025
- 6384
- 960
- 875
- 49
- 10816
- 961
- 121
- 528
- 3721
- 483
- 16
- 144
- 196
- 9964
- 7744
- 11449
- 5940
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