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 = 14 and y = 11.
- 2.If a + b = 16 and ab = 48, what is a² + b²?
- 3.If a + b = 5 and ab = 6, what is a² + b²?
- 4.Use (a + b)² = a² + 2ab + b² to find 61².
- 5.Use (a + b)² = a² + 2ab + b² to find 39².
- 6.Use (a + b)(a − b) = a² − b² to find 85 × 75.
- 7.Find the value of x² + 2xy + y² when x = 14 and y = 2.
- 8.Use (a + b)(a − b) = a² − b² to find 92 × 88.
- 9.Use (a − b)² = a² − 2ab + b² to find 27².
- 10.Use a² − b² = (a + b)(a − b) to find 23² − 13².
- 11.Use (a + b)² = a² + 2ab + b² to find 87².
- 12.Use (a + b)² = a² + 2ab + b² to find 62².
- 13.Find the value of x² − 2xy + y² when x = 4 and y = 1.
- 14.Use (a + b)² = a² + 2ab + b² to find 37².
- 15.Use (a − b)² = a² − 2ab + b² to find 47².
- 16.Use (a + b)(a − b) = a² − b² to find 96 × 84.
- 17.Use a² − b² = (a + b)(a − b) to find 92² − 73².
- 18.Find the value of x² − y² when x = 9 and y = 5.
- 19.Use (a + b)(a − b) = a² − b² to find 89 × 71.
- 20.Use (a + b)(a − b) = a² − b² to find 104 × 96.
- 21.Use (a − b)² = a² − 2ab + b² to find 13².
- 22.Use (a + b)² = a² + 2ab + b² to find 26².
- 23.Use a² − b² = (a + b)(a − b) to find 86² − 49².
- 24.Find the value of x² + 2xy + y² when x = 14 and y = 7.
- 25.Use a² − b² = (a + b)(a − b) to find 74² − 3².
- 26.Use (a − b)² = a² − 2ab + b² to find 26².
- 27.Use (a + b)² = a² + 2ab + b² to find 83².
- 28.Use (a − b)² = a² − 2ab + b² to find 84².
- 29.Use a² − b² = (a + b)(a − b) to find 21² − 18².
- 30.Find the value of x² − 2xy + y² when x = 7 and y = 4.
- 31.Use (a + b)(a − b) = a² − b² to find 37 × 23.
- 32.Use (a − b)² = a² − 2ab + b² to find 73².
- 33.Use (a − b)² = a² − 2ab + b² to find 67².
- 34.Use (a + b)² = a² + 2ab + b² to find 18².
- 35.Use (a − b)² = a² − 2ab + b² to find 57².
- 36.Use a² − b² = (a + b)(a − b) to find 24² − 12².
- 37.Use (a + b)(a − b) = a² − b² to find 77 × 63.
- 38.Use (a + b)² = a² + 2ab + b² to find 13².
- 39.If a − b = 3 and ab = 40, what is a² + b²?
- 40.Use a² − b² = (a + b)(a − b) to find 51² − 13².
Answer key
- 9
- 160
- 13
- 3721
- 1521
- 6375
- 256
- 8096
- 729
- 360
- 7569
- 3844
- 9
- 1369
- 2209
- 8064
- 3135
- 56
- 6319
- 9984
- 169
- 676
- 4995
- 441
- 5467
- 676
- 6889
- 7056
- 117
- 9
- 851
- 5329
- 4489
- 324
- 3249
- 432
- 4851
- 169
- 89
- 2432
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