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 36² − 3².
- 2.Use a² − b² = (a + b)(a − b) to find 30² − 7².
- 3.If a + b = 16 and ab = 55, what is a² + b²?
- 4.If a − b = 1 and ab = 2, what is a² + b²?
- 5.If a + b = 10 and ab = 16, what is a² + b²?
- 6.Find the value of x² − y² when x = 15 and y = 13.
- 7.Use (a + b)² = a² + 2ab + b² to find 21².
- 8.Use (a − b)² = a² − 2ab + b² to find 95².
- 9.If a − b = 5 and ab = 6, what is a² + b²?
- 10.Use (a − b)² = a² − 2ab + b² to find 89².
- 11.If a + b = 5 and ab = 4, what is a² + b²?
- 12.Use a² − b² = (a + b)(a − b) to find 45² − 24².
- 13.Use (a + b)(a − b) = a² − b² to find 38 × 22.
- 14.Use (a − b)² = a² − 2ab + b² to find 91².
- 15.Use (a − b)² = a² − 2ab + b² to find 19².
- 16.Find the value of x² − y² when x = 8 and y = 2.
- 17.Use (a − b)² = a² − 2ab + b² to find 43².
- 18.If a − b = 11 and ab = 12, what is a² + b²?
- 19.Find the value of x² − y² when x = 14 and y = 2.
- 20.Use (a + b)(a − b) = a² − b² to find 48 × 32.
- 21.If a + b = 12 and ab = 27, what is a² + b²?
- 22.Use (a + b)² = a² + 2ab + b² to find 108².
- 23.Use (a + b)(a − b) = a² − b² to find 61 × 59.
- 24.Use (a − b)² = a² − 2ab + b² to find 45².
- 25.Use (a + b)(a − b) = a² − b² to find 84 × 76.
- 26.Use a² − b² = (a + b)(a − b) to find 25² − 8².
- 27.Find the value of x² − y² when x = 4 and y = 3.
- 28.Use (a − b)² = a² − 2ab + b² to find 11².
- 29.Use a² − b² = (a + b)(a − b) to find 28² − 12².
- 30.If a − b = 2 and ab = 35, what is a² + b²?
- 31.Use (a + b)(a − b) = a² − b² to find 75 × 65.
- 32.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 33.Use (a + b)² = a² + 2ab + b² to find 44².
- 34.Use (a + b)² = a² + 2ab + b² to find 38².
- 35.If a + b = 5 and ab = 6, what is a² + b²?
- 36.Use a² − b² = (a + b)(a − b) to find 38² − 11².
- 37.If a + b = 8 and ab = 7, what is a² + b²?
- 38.Use a² − b² = (a + b)(a − b) to find 34² − 3².
- 39.If a + b = 13 and ab = 12, what is a² + b²?
- 40.Use (a − b)² = a² − 2ab + b² to find 29².
Answer key
- 1287
- 851
- 146
- 5
- 68
- 56
- 441
- 9025
- 37
- 7921
- 17
- 1449
- 836
- 8281
- 361
- 60
- 1849
- 145
- 192
- 1536
- 90
- 11664
- 3599
- 2025
- 6384
- 561
- 7
- 121
- 640
- 74
- 4875
- 399
- 1936
- 1444
- 13
- 1323
- 50
- 1147
- 145
- 841
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