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 72² − 17².
- 2.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 3.If a + b = 14 and ab = 40, what is a² + b²?
- 4.Use a² − b² = (a + b)(a − b) to find 74² − 14².
- 5.Use a² − b² = (a + b)(a − b) to find 27² − 1².
- 6.Use (a + b)(a − b) = a² − b² to find 38 × 22.
- 7.Find the value of x² + 2xy + y² when x = 15 and y = 2.
- 8.Use (a + b)² = a² + 2ab + b² to find 74².
- 9.Use (a + b)² = a² + 2ab + b² to find 16².
- 10.If a − b = 1 and ab = 30, what is a² + b²?
- 11.Find the value of x² − y² when x = 4 and y = 2.
- 12.Use (a + b)² = a² + 2ab + b² to find 11².
- 13.Find the value of x² − y² when x = 5 and y = 2.
- 14.Use (a + b)² = a² + 2ab + b² to find 44².
- 15.Use (a − b)² = a² − 2ab + b² to find 52².
- 16.Use (a − b)² = a² − 2ab + b² to find 48².
- 17.Use (a − b)² = a² − 2ab + b² to find 21².
- 18.Find the value of x² + 2xy + y² when x = 4 and y = 3.
- 19.Use (a − b)² = a² − 2ab + b² to find 39².
- 20.Use (a − b)² = a² − 2ab + b² to find 76².
- 21.Use (a − b)² = a² − 2ab + b² to find 53².
- 22.If a + b = 4 and ab = 3, what is a² + b²?
- 23.If a + b = 5 and ab = 6, what is a² + b²?
- 24.Find the value of x² − y² when x = 9 and y = 7.
- 25.Use (a + b)(a − b) = a² − b² to find 82 × 78.
- 26.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 27.Use (a − b)² = a² − 2ab + b² to find 37².
- 28.Use (a + b)(a − b) = a² − b² to find 29 × 11.
- 29.Find the value of x² − 2xy + y² when x = 3 and y = 2.
- 30.If a − b = 2 and ab = 8, what is a² + b²?
- 31.Use (a − b)² = a² − 2ab + b² to find 66².
- 32.Find the value of x² + 2xy + y² when x = 11 and y = 10.
- 33.Use (a + b)² = a² + 2ab + b² to find 32².
- 34.Find the value of x² − 2xy + y² when x = 10 and y = 3.
- 35.Use (a + b)(a − b) = a² − b² to find 98 × 82.
- 36.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 37.If a + b = 14 and ab = 48, what is a² + b²?
- 38.Use (a + b)² = a² + 2ab + b² to find 75².
- 39.Use (a + b)(a − b) = a² − b² to find 37 × 23.
- 40.Find the value of x² − y² when x = 3 and y = 2.
Answer key
- 4895
- 25
- 116
- 5280
- 728
- 836
- 289
- 5476
- 256
- 61
- 12
- 121
- 21
- 1936
- 2704
- 2304
- 441
- 49
- 1521
- 5776
- 2809
- 10
- 13
- 32
- 6396
- 384
- 1369
- 319
- 1
- 20
- 4356
- 441
- 1024
- 49
- 8036
- 3596
- 100
- 5625
- 851
- 5
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