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.If a − b = 4 and ab = 5, what is a² + b²?
- 2.Use (a + b)(a − b) = a² − b² to find 78 × 62.
- 3.Find the value of x² − 2xy + y² when x = 5 and y = 4.
- 4.Find the value of x² + 2xy + y² when x = 9 and y = 3.
- 5.Use a² − b² = (a + b)(a − b) to find 43² − 11².
- 6.Use (a − b)² = a² − 2ab + b² to find 52².
- 7.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 8.Use (a − b)² = a² − 2ab + b² to find 21².
- 9.If a + b = 21 and ab = 110, what is a² + b²?
- 10.If a − b = 5 and ab = 6, what is a² + b²?
- 11.Use a² − b² = (a + b)(a − b) to find 67² − 52².
- 12.Use (a + b)² = a² + 2ab + b² to find 95².
- 13.Use (a − b)² = a² − 2ab + b² to find 62².
- 14.Use (a + b)(a − b) = a² − b² to find 67 × 53.
- 15.Find the value of x² − 2xy + y² when x = 5 and y = 3.
- 16.Use (a − b)² = a² − 2ab + b² to find 35².
- 17.Use (a − b)² = a² − 2ab + b² to find 31².
- 18.Use (a + b)² = a² + 2ab + b² to find 49².
- 19.Use (a + b)² = a² + 2ab + b² to find 37².
- 20.If a − b = 7 and ab = 18, what is a² + b²?
- 21.Use a² − b² = (a + b)(a − b) to find 57² − 23².
- 22.Use (a + b)² = a² + 2ab + b² to find 35².
- 23.Find the value of x² − y² when x = 11 and y = 3.
- 24.Use (a + b)(a − b) = a² − b² to find 101 × 99.
- 25.Use (a − b)² = a² − 2ab + b² to find 69².
- 26.Use a² − b² = (a + b)(a − b) to find 63² − 50².
- 27.If a + b = 10 and ab = 9, what is a² + b²?
- 28.Find the value of x² − 2xy + y² when x = 8 and y = 1.
- 29.Use a² − b² = (a + b)(a − b) to find 36² − 23².
- 30.Use a² − b² = (a + b)(a − b) to find 49² − 8².
- 31.Find the value of x² − y² when x = 6 and y = 4.
- 32.Use a² − b² = (a + b)(a − b) to find 32² − 2².
- 33.Use a² − b² = (a + b)(a − b) to find 76² − 5².
- 34.Use a² − b² = (a + b)(a − b) to find 95² − 26².
- 35.If a + b = 12 and ab = 11, what is a² + b²?
- 36.Use (a + b)² = a² + 2ab + b² to find 83².
- 37.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 38.Use (a + b)² = a² + 2ab + b² to find 52².
- 39.Find the value of x² − y² when x = 7 and y = 2.
- 40.Use (a − b)² = a² − 2ab + b² to find 23².
Answer key
- 26
- 4836
- 1
- 144
- 1728
- 2704
- 1551
- 441
- 221
- 37
- 1785
- 9025
- 3844
- 3551
- 4
- 1225
- 961
- 2401
- 1369
- 85
- 2720
- 1225
- 112
- 9999
- 4761
- 1469
- 82
- 49
- 767
- 2337
- 20
- 1020
- 5751
- 8349
- 122
- 6889
- 3596
- 2704
- 45
- 529
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