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 = 7 and ab = 44, what is a² + b²?
- 2.Use (a − b)² = a² − 2ab + b² to find 49².
- 3.If a − b = 2 and ab = 3, what is a² + b²?
- 4.Use (a − b)² = a² − 2ab + b² to find 46².
- 5.Use (a − b)² = a² − 2ab + b² to find 91².
- 6.Use (a + b)(a − b) = a² − b² to find 73 × 67.
- 7.Use (a + b)(a − b) = a² − b² to find 26 × 14.
- 8.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 9.Use (a + b)² = a² + 2ab + b² to find 85².
- 10.Use a² − b² = (a + b)(a − b) to find 56² − 37².
- 11.If a − b = 1 and ab = 2, what is a² + b²?
- 12.Use a² − b² = (a + b)(a − b) to find 52² − 11².
- 13.Find the value of x² + 2xy + y² when x = 5 and y = 4.
- 14.Find the value of x² − y² when x = 7 and y = 5.
- 15.Use a² − b² = (a + b)(a − b) to find 23² − 17².
- 16.Use a² − b² = (a + b)(a − b) to find 65² − 12².
- 17.Use (a − b)² = a² − 2ab + b² to find 25².
- 18.If a − b = 2 and ab = 8, what is a² + b²?
- 19.Use a² − b² = (a + b)(a − b) to find 98² − 14².
- 20.If a − b = 10 and ab = 11, what is a² + b²?
- 21.Use (a + b)² = a² + 2ab + b² to find 37².
- 22.Use (a + b)² = a² + 2ab + b² to find 11².
- 23.Use a² − b² = (a + b)(a − b) to find 59² − 24².
- 24.Find the value of x² + 2xy + y² when x = 12 and y = 8.
- 25.If a − b = 5 and ab = 36, what is a² + b²?
- 26.Use (a + b)(a − b) = a² − b² to find 42 × 38.
- 27.Use (a + b)(a − b) = a² − b² to find 32 × 28.
- 28.Use a² − b² = (a + b)(a − b) to find 36² − 10².
- 29.Use (a − b)² = a² − 2ab + b² to find 78².
- 30.Use (a + b)² = a² + 2ab + b² to find 97².
- 31.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 32.Use (a + b)(a − b) = a² − b² to find 89 × 71.
- 33.Find the value of x² − 2xy + y² when x = 7 and y = 2.
- 34.Use (a − b)² = a² − 2ab + b² to find 51².
- 35.Use (a + b)² = a² + 2ab + b² to find 64².
- 36.Use (a + b)(a − b) = a² − b² to find 49 × 31.
- 37.Use (a + b)(a − b) = a² − b² to find 41 × 39.
- 38.If a − b = 1 and ab = 42, what is a² + b²?
- 39.Find the value of x² − y² when x = 4 and y = 2.
- 40.Use (a + b)² = a² + 2ab + b² to find 73².
Answer key
- 137
- 2401
- 10
- 2116
- 8281
- 4891
- 364
- 399
- 7225
- 1767
- 5
- 2583
- 81
- 24
- 240
- 4081
- 625
- 20
- 9408
- 122
- 1369
- 121
- 2905
- 400
- 97
- 1596
- 896
- 1196
- 6084
- 9409
- 8091
- 6319
- 25
- 2601
- 4096
- 1519
- 1599
- 85
- 12
- 5329
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