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 53² − 47².
- 2.Use (a − b)² = a² − 2ab + b² to find 31².
- 3.Use (a − b)² = a² − 2ab + b² to find 55².
- 4.Find the value of x² − y² when x = 3 and y = 1.
- 5.If a + b = 5 and ab = 6, what is a² + b²?
- 6.Use a² − b² = (a + b)(a − b) to find 83² − 11².
- 7.Use (a + b)(a − b) = a² − b² to find 22 × 18.
- 8.Use a² − b² = (a + b)(a − b) to find 43² − 13².
- 9.Use (a + b)² = a² + 2ab + b² to find 31².
- 10.Use a² − b² = (a + b)(a − b) to find 67² − 34².
- 11.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 12.Use (a + b)² = a² + 2ab + b² to find 24².
- 13.Use a² − b² = (a + b)(a − b) to find 42² − 11².
- 14.Find the value of x² − 2xy + y² when x = 4 and y = 1.
- 15.Use (a − b)² = a² − 2ab + b² to find 68².
- 16.Use (a + b)² = a² + 2ab + b² to find 11².
- 17.Use (a − b)² = a² − 2ab + b² to find 36².
- 18.Use (a + b)² = a² + 2ab + b² to find 32².
- 19.Find the value of x² + 2xy + y² when x = 6 and y = 2.
- 20.Use (a − b)² = a² − 2ab + b² to find 21².
- 21.If a + b = 4 and ab = 3, what is a² + b²?
- 22.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 23.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 24.Find the value of x² + 2xy + y² when x = 13 and y = 9.
- 25.If a + b = 22 and ab = 120, what is a² + b²?
- 26.Use a² − b² = (a + b)(a − b) to find 27² − 2².
- 27.Use (a + b)² = a² + 2ab + b² to find 74².
- 28.Use a² − b² = (a + b)(a − b) to find 66² − 16².
- 29.Use (a − b)² = a² − 2ab + b² to find 37².
- 30.Find the value of x² − 2xy + y² when x = 10 and y = 1.
- 31.Find the value of x² − 2xy + y² when x = 9 and y = 7.
- 32.If a + b = 16 and ab = 63, what is a² + b²?
- 33.Use (a − b)² = a² − 2ab + b² to find 79².
- 34.Find the value of x² − 2xy + y² when x = 7 and y = 6.
- 35.Use (a + b)(a − b) = a² − b² to find 108 × 92.
- 36.Use a² − b² = (a + b)(a − b) to find 83² − 9².
- 37.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 38.Use (a + b)² = a² + 2ab + b² to find 68².
- 39.Find the value of x² − 2xy + y² when x = 8 and y = 1.
- 40.Find the value of x² + 2xy + y² when x = 7 and y = 3.
Answer key
- 600
- 961
- 3025
- 8
- 13
- 6768
- 396
- 1680
- 961
- 3333
- 875
- 576
- 1643
- 9
- 4624
- 121
- 1296
- 1024
- 64
- 441
- 10
- 391
- 3596
- 484
- 244
- 725
- 5476
- 4100
- 1369
- 81
- 4
- 130
- 6241
- 1
- 9936
- 6808
- 2484
- 4624
- 49
- 100
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