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 − y² when x = 4 and y = 2.
- 2.Use (a − b)² = a² − 2ab + b² to find 28².
- 3.If a + b = 8 and ab = 12, what is a² + b²?
- 4.Use (a − b)² = a² − 2ab + b² to find 38².
- 5.Use (a + b)(a − b) = a² − b² to find 91 × 89.
- 6.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 7.If a + b = 6 and ab = 5, what is a² + b²?
- 8.Find the value of x² − 2xy + y² when x = 6 and y = 1.
- 9.Find the value of x² − y² when x = 5 and y = 4.
- 10.Use a² − b² = (a + b)(a − b) to find 63² − 58².
- 11.Use (a − b)² = a² − 2ab + b² to find 55².
- 12.If a + b = 3 and ab = 2, what is a² + b²?
- 13.If a + b = 14 and ab = 33, what is a² + b²?
- 14.Use (a − b)² = a² − 2ab + b² to find 18².
- 15.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 16.If a + b = 10 and ab = 24, what is a² + b²?
- 17.Use (a − b)² = a² − 2ab + b² to find 75².
- 18.If a + b = 9 and ab = 14, what is a² + b²?
- 19.Use (a − b)² = a² − 2ab + b² to find 79².
- 20.Use (a − b)² = a² − 2ab + b² to find 59².
- 21.Use (a + b)² = a² + 2ab + b² to find 24².
- 22.Use (a + b)² = a² + 2ab + b² to find 76².
- 23.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 24.Find the value of x² − y² when x = 3 and y = 2.
- 25.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 26.Use (a + b)² = a² + 2ab + b² to find 81².
- 27.Use a² − b² = (a + b)(a − b) to find 62² − 59².
- 28.Use (a + b)² = a² + 2ab + b² to find 91².
- 29.Use (a + b)² = a² + 2ab + b² to find 71².
- 30.Use (a + b)² = a² + 2ab + b² to find 21².
- 31.Use (a − b)² = a² − 2ab + b² to find 29².
- 32.Use a² − b² = (a + b)(a − b) to find 40² − 6².
- 33.If a − b = 5 and ab = 24, what is a² + b²?
- 34.Use (a + b)² = a² + 2ab + b² to find 94².
- 35.Use a² − b² = (a + b)(a − b) to find 63² − 32².
- 36.Find the value of x² − 2xy + y² when x = 6 and y = 2.
- 37.Find the value of x² + 2xy + y² when x = 5 and y = 2.
- 38.Use (a + b)² = a² + 2ab + b² to find 51².
- 39.Use a² − b² = (a + b)(a − b) to find 27² − 22².
- 40.If a − b = 5 and ab = 6, what is a² + b²?
Answer key
- 12
- 784
- 40
- 1444
- 8099
- 884
- 26
- 25
- 9
- 605
- 3025
- 5
- 130
- 324
- 2484
- 52
- 5625
- 53
- 6241
- 3481
- 576
- 5776
- 875
- 5
- 1591
- 6561
- 363
- 8281
- 5041
- 441
- 841
- 1564
- 73
- 8836
- 2945
- 16
- 49
- 2601
- 245
- 37
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