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 = 8 and y = 3.
- 2.Use a² − b² = (a + b)(a − b) to find 52² − 10².
- 3.Use a² − b² = (a + b)(a − b) to find 65² − 23².
- 4.Use (a + b)² = a² + 2ab + b² to find 41².
- 5.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 6.Use (a − b)² = a² − 2ab + b² to find 18².
- 7.If a + b = 11 and ab = 28, what is a² + b²?
- 8.Use (a + b)(a − b) = a² − b² to find 59 × 41.
- 9.Use a² − b² = (a + b)(a − b) to find 30² − 21².
- 10.Use a² − b² = (a + b)(a − b) to find 42² − 17².
- 11.Use (a − b)² = a² − 2ab + b² to find 81².
- 12.Use a² − b² = (a + b)(a − b) to find 36² − 30².
- 13.Use (a − b)² = a² − 2ab + b² to find 94².
- 14.Use a² − b² = (a + b)(a − b) to find 35² − 15².
- 15.Use (a + b)(a − b) = a² − b² to find 83 × 77.
- 16.Use (a − b)² = a² − 2ab + b² to find 68².
- 17.Use (a + b)(a − b) = a² − b² to find 101 × 99.
- 18.Find the value of x² + 2xy + y² when x = 10 and y = 1.
- 19.Find the value of x² − 2xy + y² when x = 9 and y = 3.
- 20.If a + b = 18 and ab = 72, what is a² + b²?
- 21.Use (a − b)² = a² − 2ab + b² to find 35².
- 22.If a − b = 5 and ab = 50, what is a² + b²?
- 23.Use (a + b)(a − b) = a² − b² to find 99 × 81.
- 24.Use (a − b)² = a² − 2ab + b² to find 62².
- 25.Use (a + b)(a − b) = a² − b² to find 64 × 56.
- 26.Use (a + b)² = a² + 2ab + b² to find 18².
- 27.If a + b = 12 and ab = 27, what is a² + b²?
- 28.Find the value of x² − y² when x = 7 and y = 1.
- 29.Use (a − b)² = a² − 2ab + b² to find 73².
- 30.Use a² − b² = (a + b)(a − b) to find 38² − 14².
- 31.Find the value of x² − y² when x = 7 and y = 6.
- 32.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 33.Use a² − b² = (a + b)(a − b) to find 48² − 30².
- 34.Use (a + b)² = a² + 2ab + b² to find 11².
- 35.Find the value of x² + 2xy + y² when x = 9 and y = 8.
- 36.Find the value of x² − y² when x = 11 and y = 1.
- 37.Use (a + b)² = a² + 2ab + b² to find 43².
- 38.Use (a + b)² = a² + 2ab + b² to find 31².
- 39.Use (a + b)² = a² + 2ab + b² to find 34².
- 40.Use (a + b)² = a² + 2ab + b² to find 38².
Answer key
- 121
- 2604
- 3696
- 1681
- 391
- 324
- 65
- 2419
- 459
- 1475
- 6561
- 396
- 8836
- 1000
- 6391
- 4624
- 9999
- 121
- 36
- 180
- 1225
- 125
- 8019
- 3844
- 3584
- 324
- 90
- 48
- 5329
- 1248
- 13
- 25
- 1404
- 121
- 289
- 120
- 1849
- 961
- 1156
- 1444
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