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 a² − b² = (a + b)(a − b) to find 85² − 66².
- 2.Use a² − b² = (a + b)(a − b) to find 76² − 21².
- 3.Use (a − b)² = a² − 2ab + b² to find 43².
- 4.Use a² − b² = (a + b)(a − b) to find 31² − 7².
- 5.Use (a + b)(a − b) = a² − b² to find 104 × 96.
- 6.Use a² − b² = (a + b)(a − b) to find 95² − 49².
- 7.Use (a − b)² = a² − 2ab + b² to find 19².
- 8.If a + b = 16 and ab = 48, what is a² + b²?
- 9.Find the value of x² − y² when x = 12 and y = 7.
- 10.Use (a + b)² = a² + 2ab + b² to find 24².
- 11.Use (a + b)² = a² + 2ab + b² to find 43².
- 12.Use (a + b)² = a² + 2ab + b² to find 92².
- 13.Use a² − b² = (a + b)(a − b) to find 35² − 8².
- 14.Use (a − b)² = a² − 2ab + b² to find 76².
- 15.Use (a + b)(a − b) = a² − b² to find 107 × 93.
- 16.Use (a + b)(a − b) = a² − b² to find 68 × 52.
- 17.If a − b = 1 and ab = 2, what is a² + b²?
- 18.Use (a + b)² = a² + 2ab + b² to find 62².
- 19.Find the value of x² − 2xy + y² when x = 11 and y = 10.
- 20.Use (a + b)(a − b) = a² − b² to find 75 × 65.
- 21.Use (a + b)² = a² + 2ab + b² to find 83².
- 22.Use a² − b² = (a + b)(a − b) to find 81² − 13².
- 23.Use (a + b)(a − b) = a² − b² to find 82 × 78.
- 24.Use a² − b² = (a + b)(a − b) to find 95² − 39².
- 25.Use (a + b)² = a² + 2ab + b² to find 38².
- 26.Use (a + b)² = a² + 2ab + b² to find 36².
- 27.Use (a + b)(a − b) = a² − b² to find 26 × 14.
- 28.Find the value of x² − 2xy + y² when x = 6 and y = 1.
- 29.Use (a − b)² = a² − 2ab + b² to find 68².
- 30.Use a² − b² = (a + b)(a − b) to find 30² − 16².
- 31.Find the value of x² + 2xy + y² when x = 8 and y = 5.
- 32.If a + b = 5 and ab = 6, what is a² + b²?
- 33.Find the value of x² + 2xy + y² when x = 6 and y = 4.
- 34.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 35.Find the value of x² + 2xy + y² when x = 12 and y = 8.
- 36.Find the value of x² + 2xy + y² when x = 3 and y = 1.
- 37.Find the value of x² + 2xy + y² when x = 8 and y = 4.
- 38.Find the value of x² + 2xy + y² when x = 9 and y = 4.
- 39.Use (a − b)² = a² − 2ab + b² to find 22².
- 40.If a + b = 8 and ab = 15, what is a² + b²?
Answer key
- 2869
- 5335
- 1849
- 912
- 9984
- 6624
- 361
- 160
- 95
- 576
- 1849
- 8464
- 1161
- 5776
- 9951
- 3536
- 5
- 3844
- 1
- 4875
- 6889
- 6392
- 6396
- 7504
- 1444
- 1296
- 364
- 25
- 4624
- 644
- 169
- 13
- 100
- 384
- 400
- 16
- 144
- 169
- 484
- 34
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