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 = 1 and ab = 30, what is a² + b²?
- 2.Use (a − b)² = a² − 2ab + b² to find 35².
- 3.Find the value of x² + 2xy + y² when x = 5 and y = 4.
- 4.If a − b = 1 and ab = 2, what is a² + b²?
- 5.Use a² − b² = (a + b)(a − b) to find 42² − 9².
- 6.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 7.If a + b = 4 and ab = 3, what is a² + b²?
- 8.Use (a + b)² = a² + 2ab + b² to find 103².
- 9.Use (a + b)² = a² + 2ab + b² to find 53².
- 10.Use a² − b² = (a + b)(a − b) to find 34² − 31².
- 11.Use a² − b² = (a + b)(a − b) to find 70² − 19².
- 12.Use (a + b)(a − b) = a² − b² to find 33 × 27.
- 13.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 14.Find the value of x² + 2xy + y² when x = 9 and y = 8.
- 15.If a − b = 4 and ab = 21, what is a² + b²?
- 16.Find the value of x² + 2xy + y² when x = 4 and y = 1.
- 17.Find the value of x² − 2xy + y² when x = 4 and y = 3.
- 18.Use a² − b² = (a + b)(a − b) to find 92² − 3².
- 19.If a − b = 1 and ab = 12, what is a² + b²?
- 20.If a + b = 13 and ab = 22, what is a² + b²?
- 21.Use (a + b)² = a² + 2ab + b² to find 29².
- 22.Use (a + b)(a − b) = a² − b² to find 25 × 15.
- 23.Use a² − b² = (a + b)(a − b) to find 60² − 58².
- 24.Find the value of x² − 2xy + y² when x = 6 and y = 4.
- 25.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 26.Use (a + b)² = a² + 2ab + b² to find 21².
- 27.Use (a + b)² = a² + 2ab + b² to find 45².
- 28.Use (a − b)² = a² − 2ab + b² to find 17².
- 29.Use a² − b² = (a + b)(a − b) to find 69² − 46².
- 30.Use (a + b)(a − b) = a² − b² to find 29 × 11.
- 31.Use a² − b² = (a + b)(a − b) to find 97² − 66².
- 32.Use a² − b² = (a + b)(a − b) to find 65² − 12².
- 33.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 34.Use (a + b)² = a² + 2ab + b² to find 107².
- 35.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 36.If a + b = 3 and ab = 2, what is a² + b²?
- 37.Use a² − b² = (a + b)(a − b) to find 48² − 29².
- 38.Use (a + b)² = a² + 2ab + b² to find 59².
- 39.Use (a − b)² = a² − 2ab + b² to find 18².
- 40.Use a² − b² = (a + b)(a − b) to find 52² − 26².
Answer key
- 61
- 1225
- 81
- 5
- 1683
- 399
- 10
- 10609
- 2809
- 195
- 4539
- 891
- 884
- 289
- 58
- 25
- 1
- 8455
- 25
- 125
- 841
- 375
- 236
- 4
- 4899
- 441
- 2025
- 289
- 2645
- 319
- 5053
- 4081
- 864
- 11449
- 25
- 5
- 1463
- 3481
- 324
- 2028
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