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 + 2xy + y² when x = 6 and y = 5.
- 2.If a + b = 16 and ab = 60, what is a² + b²?
- 3.If a + b = 3 and ab = 2, what is a² + b²?
- 4.Use (a + b)² = a² + 2ab + b² to find 51².
- 5.Use (a + b)² = a² + 2ab + b² to find 94².
- 6.If a + b = 12 and ab = 11, what is a² + b²?
- 7.Find the value of x² − 2xy + y² when x = 15 and y = 4.
- 8.Use (a − b)² = a² − 2ab + b² to find 39².
- 9.Use (a + b)² = a² + 2ab + b² to find 89².
- 10.If a − b = 1 and ab = 90, what is a² + b²?
- 11.Use (a − b)² = a² − 2ab + b² to find 27².
- 12.Use (a + b)² = a² + 2ab + b² to find 93².
- 13.Use a² − b² = (a + b)(a − b) to find 40² − 17².
- 14.Use a² − b² = (a + b)(a − b) to find 66² − 65².
- 15.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 16.Find the value of x² − y² when x = 15 and y = 6.
- 17.Use (a + b)(a − b) = a² − b² to find 55 × 45.
- 18.Use (a + b)² = a² + 2ab + b² to find 43².
- 19.Use a² − b² = (a + b)(a − b) to find 30² − 13².
- 20.Find the value of x² − y² when x = 7 and y = 2.
- 21.Use (a + b)² = a² + 2ab + b² to find 82².
- 22.Use (a − b)² = a² − 2ab + b² to find 17².
- 23.Find the value of x² + 2xy + y² when x = 4 and y = 1.
- 24.Use a² − b² = (a + b)(a − b) to find 92² − 48².
- 25.Use a² − b² = (a + b)(a − b) to find 22² − 6².
- 26.If a + b = 9 and ab = 20, what is a² + b²?
- 27.Use (a − b)² = a² − 2ab + b² to find 89².
- 28.Use a² − b² = (a + b)(a − b) to find 40² − 13².
- 29.Use (a + b)² = a² + 2ab + b² to find 95².
- 30.Use (a + b)(a − b) = a² − b² to find 74 × 66.
- 31.Use (a + b)² = a² + 2ab + b² to find 107².
- 32.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 33.Find the value of x² + 2xy + y² when x = 11 and y = 9.
- 34.Use a² − b² = (a + b)(a − b) to find 54² − 53².
- 35.If a + b = 8 and ab = 12, what is a² + b²?
- 36.Use a² − b² = (a + b)(a − b) to find 64² − 5².
- 37.Use (a − b)² = a² − 2ab + b² to find 75².
- 38.Use (a − b)² = a² − 2ab + b² to find 92².
- 39.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 40.Use a² − b² = (a + b)(a − b) to find 81² − 45².
Answer key
- 121
- 136
- 5
- 2601
- 8836
- 122
- 121
- 1521
- 7921
- 181
- 729
- 8649
- 1311
- 131
- 3596
- 189
- 2475
- 1849
- 731
- 45
- 6724
- 289
- 25
- 6160
- 448
- 41
- 7921
- 1431
- 9025
- 4884
- 11449
- 2484
- 400
- 107
- 40
- 4071
- 5625
- 8464
- 25
- 4536
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