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 = 10 and y = 4.
- 2.Use (a − b)² = a² − 2ab + b² to find 32².
- 3.If a − b = 3 and ab = 4, what is a² + b²?
- 4.Use a² − b² = (a + b)(a − b) to find 58² − 3².
- 5.Find the value of x² − y² when x = 14 and y = 2.
- 6.Find the value of x² − 2xy + y² when x = 4 and y = 1.
- 7.Use (a + b)² = a² + 2ab + b² to find 107².
- 8.Use (a + b)² = a² + 2ab + b² to find 85².
- 9.Find the value of x² − y² when x = 7 and y = 6.
- 10.Use (a − b)² = a² − 2ab + b² to find 63².
- 11.Use a² − b² = (a + b)(a − b) to find 43² − 39².
- 12.Use (a + b)² = a² + 2ab + b² to find 96².
- 13.Use (a + b)(a − b) = a² − b² to find 27 × 13.
- 14.Find the value of x² − y² when x = 9 and y = 8.
- 15.Use (a + b)² = a² + 2ab + b² to find 17².
- 16.Use a² − b² = (a + b)(a − b) to find 69² − 17².
- 17.Find the value of x² − 2xy + y² when x = 14 and y = 7.
- 18.Use a² − b² = (a + b)(a − b) to find 82² − 45².
- 19.Use (a + b)² = a² + 2ab + b² to find 97².
- 20.Use (a + b)² = a² + 2ab + b² to find 56².
- 21.Find the value of x² + 2xy + y² when x = 13 and y = 7.
- 22.Use (a + b)² = a² + 2ab + b² to find 58².
- 23.Find the value of x² − y² when x = 12 and y = 7.
- 24.Use a² − b² = (a + b)(a − b) to find 78² − 40².
- 25.If a + b = 12 and ab = 20, what is a² + b²?
- 26.Use (a + b)² = a² + 2ab + b² to find 103².
- 27.If a + b = 13 and ab = 22, what is a² + b²?
- 28.Use (a + b)² = a² + 2ab + b² to find 41².
- 29.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 30.Find the value of x² − 2xy + y² when x = 12 and y = 3.
- 31.If a + b = 18 and ab = 77, what is a² + b²?
- 32.If a + b = 11 and ab = 24, what is a² + b²?
- 33.Use (a + b)² = a² + 2ab + b² to find 91².
- 34.If a + b = 5 and ab = 6, what is a² + b²?
- 35.Use (a + b)(a − b) = a² − b² to find 97 × 83.
- 36.Use (a + b)(a − b) = a² − b² to find 69 × 51.
- 37.Use (a − b)² = a² − 2ab + b² to find 14².
- 38.Use a² − b² = (a + b)(a − b) to find 40² − 5².
- 39.Use (a − b)² = a² − 2ab + b² to find 67².
- 40.Use (a + b)(a − b) = a² − b² to find 81 × 79.
Answer key
- 196
- 1024
- 17
- 3355
- 192
- 9
- 11449
- 7225
- 13
- 3969
- 328
- 9216
- 351
- 17
- 289
- 4472
- 49
- 4699
- 9409
- 3136
- 400
- 3364
- 95
- 4484
- 104
- 10609
- 125
- 1681
- 864
- 81
- 170
- 73
- 8281
- 13
- 8051
- 3519
- 196
- 1575
- 4489
- 6399
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