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 53² − 32².
- 2.Use (a + b)² = a² + 2ab + b² to find 75².
- 3.Find the value of x² + 2xy + y² when x = 12 and y = 1.
- 4.Use (a + b)² = a² + 2ab + b² to find 51².
- 5.If a + b = 4 and ab = 3, what is a² + b²?
- 6.Find the value of x² − y² when x = 11 and y = 1.
- 7.Find the value of x² + 2xy + y² when x = 13 and y = 4.
- 8.Use (a + b)² = a² + 2ab + b² to find 54².
- 9.Find the value of x² − 2xy + y² when x = 14 and y = 8.
- 10.If a + b = 9 and ab = 18, what is a² + b²?
- 11.Use a² − b² = (a + b)(a − b) to find 23² − 5².
- 12.Find the value of x² − 2xy + y² when x = 10 and y = 4.
- 13.Use (a + b)² = a² + 2ab + b² to find 28².
- 14.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 15.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 16.If a − b = 1 and ab = 2, what is a² + b²?
- 17.Find the value of x² − y² when x = 4 and y = 2.
- 18.Use (a + b)(a − b) = a² − b² to find 45 × 35.
- 19.Use a² − b² = (a + b)(a − b) to find 64² − 19².
- 20.Use (a − b)² = a² − 2ab + b² to find 43².
- 21.Use (a + b)² = a² + 2ab + b² to find 34².
- 22.Use (a − b)² = a² − 2ab + b² to find 16².
- 23.Use (a + b)² = a² + 2ab + b² to find 76².
- 24.Use (a − b)² = a² − 2ab + b² to find 42².
- 25.If a + b = 10 and ab = 24, what is a² + b²?
- 26.Use (a + b)(a − b) = a² − b² to find 31 × 29.
- 27.Use (a + b)² = a² + 2ab + b² to find 21².
- 28.If a − b = 6 and ab = 16, what is a² + b²?
- 29.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 30.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 31.Use (a + b)(a − b) = a² − b² to find 78 × 62.
- 32.Use (a − b)² = a² − 2ab + b² to find 35².
- 33.Use (a + b)² = a² + 2ab + b² to find 91².
- 34.Use (a + b)² = a² + 2ab + b² to find 71².
- 35.Use (a + b)² = a² + 2ab + b² to find 31².
- 36.Use a² − b² = (a + b)(a − b) to find 61² − 20².
- 37.Use (a + b)² = a² + 2ab + b² to find 78².
- 38.Use (a + b)² = a² + 2ab + b² to find 81².
- 39.Use a² − b² = (a + b)(a − b) to find 80² − 21².
- 40.Use (a − b)² = a² − 2ab + b² to find 97².
Answer key
- 1785
- 5625
- 169
- 2601
- 10
- 120
- 289
- 2916
- 36
- 45
- 504
- 36
- 784
- 3591
- 384
- 5
- 12
- 1575
- 3735
- 1849
- 1156
- 256
- 5776
- 1764
- 52
- 899
- 441
- 68
- 1551
- 399
- 4836
- 1225
- 8281
- 5041
- 961
- 3321
- 6084
- 6561
- 5959
- 9409
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