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 = 12 and y = 2.
- 2.Use (a − b)² = a² − 2ab + b² to find 82².
- 3.Find the value of x² + 2xy + y² when x = 7 and y = 2.
- 4.Find the value of x² − 2xy + y² when x = 4 and y = 2.
- 5.Use a² − b² = (a + b)(a − b) to find 78² − 72².
- 6.Use a² − b² = (a + b)(a − b) to find 22² − 5².
- 7.Use (a + b)(a − b) = a² − b² to find 107 × 93.
- 8.Use (a + b)² = a² + 2ab + b² to find 91².
- 9.Use a² − b² = (a + b)(a − b) to find 49² − 12².
- 10.Use (a + b)(a − b) = a² − b² to find 58 × 42.
- 11.Find the value of x² − 2xy + y² when x = 15 and y = 4.
- 12.Use a² − b² = (a + b)(a − b) to find 50² − 46².
- 13.Use (a − b)² = a² − 2ab + b² to find 38².
- 14.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 15.Find the value of x² + 2xy + y² when x = 14 and y = 7.
- 16.Use (a + b)² = a² + 2ab + b² to find 48².
- 17.Use (a + b)² = a² + 2ab + b² to find 37².
- 18.Use a² − b² = (a + b)(a − b) to find 57² − 48².
- 19.Use (a + b)(a − b) = a² − b² to find 104 × 96.
- 20.Use (a + b)(a − b) = a² − b² to find 55 × 45.
- 21.Use (a + b)² = a² + 2ab + b² to find 35².
- 22.Use a² − b² = (a + b)(a − b) to find 60² − 47².
- 23.Use a² − b² = (a + b)(a − b) to find 80² − 37².
- 24.Use a² − b² = (a + b)(a − b) to find 23² − 16².
- 25.Use (a − b)² = a² − 2ab + b² to find 23².
- 26.Use (a + b)² = a² + 2ab + b² to find 46².
- 27.Use a² − b² = (a + b)(a − b) to find 47² − 36².
- 28.Use a² − b² = (a + b)(a − b) to find 96² − 85².
- 29.Find the value of x² − y² when x = 4 and y = 1.
- 30.Use a² − b² = (a + b)(a − b) to find 30² − 5².
- 31.Use a² − b² = (a + b)(a − b) to find 79² − 75².
- 32.Find the value of x² − 2xy + y² when x = 6 and y = 4.
- 33.Find the value of x² + 2xy + y² when x = 5 and y = 4.
- 34.Use (a + b)² = a² + 2ab + b² to find 92².
- 35.Use (a + b)(a − b) = a² − b² to find 25 × 15.
- 36.If a − b = 3 and ab = 88, what is a² + b²?
- 37.Use a² − b² = (a + b)(a − b) to find 72² − 36².
- 38.Use (a + b)² = a² + 2ab + b² to find 41².
- 39.Use (a + b)(a − b) = a² − b² to find 91 × 89.
- 40.Use (a − b)² = a² − 2ab + b² to find 55².
Answer key
- 100
- 6724
- 81
- 4
- 900
- 459
- 9951
- 8281
- 2257
- 2436
- 121
- 384
- 1444
- 3591
- 441
- 2304
- 1369
- 945
- 9984
- 2475
- 1225
- 1391
- 5031
- 273
- 529
- 2116
- 913
- 1991
- 15
- 875
- 616
- 4
- 81
- 8464
- 375
- 185
- 3888
- 1681
- 8099
- 3025
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