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 (a − b)² = a² − 2ab + b² to find 97².
- 2.Use (a + b)² = a² + 2ab + b² to find 41².
- 3.Use a² − b² = (a + b)(a − b) to find 96² − 8².
- 4.Use (a + b)(a − b) = a² − b² to find 53 × 47.
- 5.Find the value of x² + 2xy + y² when x = 14 and y = 2.
- 6.Find the value of x² − 2xy + y² when x = 11 and y = 1.
- 7.If a + b = 7 and ab = 12, what is a² + b²?
- 8.Use (a + b)² = a² + 2ab + b² to find 102².
- 9.Use a² − b² = (a + b)(a − b) to find 20² − 5².
- 10.Find the value of x² + 2xy + y² when x = 5 and y = 4.
- 11.If a − b = 2 and ab = 48, what is a² + b²?
- 12.Find the value of x² − 2xy + y² when x = 13 and y = 2.
- 13.Use a² − b² = (a + b)(a − b) to find 70² − 57².
- 14.Use (a − b)² = a² − 2ab + b² to find 11².
- 15.Use (a + b)(a − b) = a² − b² to find 84 × 76.
- 16.Use (a + b)(a − b) = a² − b² to find 67 × 53.
- 17.Find the value of x² − 2xy + y² when x = 9 and y = 8.
- 18.Find the value of x² + 2xy + y² when x = 12 and y = 2.
- 19.Use (a + b)² = a² + 2ab + b² to find 12².
- 20.Use (a + b)² = a² + 2ab + b² to find 98².
- 21.Use (a + b)(a − b) = a² − b² to find 49 × 31.
- 22.Use (a + b)² = a² + 2ab + b² to find 29².
- 23.If a + b = 14 and ab = 40, what is a² + b²?
- 24.Use a² − b² = (a + b)(a − b) to find 27² − 13².
- 25.Use (a − b)² = a² − 2ab + b² to find 43².
- 26.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 27.If a + b = 9 and ab = 8, what is a² + b²?
- 28.Use (a − b)² = a² − 2ab + b² to find 18².
- 29.Use (a + b)² = a² + 2ab + b² to find 68².
- 30.If a + b = 16 and ab = 48, what is a² + b²?
- 31.Use (a − b)² = a² − 2ab + b² to find 45².
- 32.Use a² − b² = (a + b)(a − b) to find 76² − 33².
- 33.Use a² − b² = (a + b)(a − b) to find 91² − 21².
- 34.If a − b = 3 and ab = 28, what is a² + b²?
- 35.Use (a + b)² = a² + 2ab + b² to find 81².
- 36.Use (a + b)² = a² + 2ab + b² to find 13².
- 37.Use (a + b)(a − b) = a² − b² to find 57 × 43.
- 38.Use (a − b)² = a² − 2ab + b² to find 52².
- 39.Use a² − b² = (a + b)(a − b) to find 63² − 51².
- 40.Use (a + b)(a − b) = a² − b² to find 106 × 94.
Answer key
- 9409
- 1681
- 9152
- 2491
- 256
- 100
- 25
- 10404
- 375
- 81
- 100
- 121
- 1651
- 121
- 6384
- 3551
- 1
- 196
- 144
- 9604
- 1519
- 841
- 116
- 560
- 1849
- 6336
- 65
- 324
- 4624
- 160
- 2025
- 4687
- 7840
- 65
- 6561
- 169
- 2451
- 2704
- 1368
- 9964
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