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 15².
- 2.If a − b = 1 and ab = 6, what is a² + b²?
- 3.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 4.Use (a − b)² = a² − 2ab + b² to find 79².
- 5.Find the value of x² − 2xy + y² when x = 4 and y = 1.
- 6.Use (a + b)² = a² + 2ab + b² to find 63².
- 7.Use (a + b)² = a² + 2ab + b² to find 33².
- 8.Use (a + b)² = a² + 2ab + b² to find 29².
- 9.Find the value of x² − y² when x = 12 and y = 7.
- 10.Use (a − b)² = a² − 2ab + b² to find 65².
- 11.Find the value of x² − y² when x = 8 and y = 1.
- 12.Use (a + b)² = a² + 2ab + b² to find 13².
- 13.Use a² − b² = (a + b)(a − b) to find 63² − 6².
- 14.Use (a − b)² = a² − 2ab + b² to find 61².
- 15.Use (a − b)² = a² − 2ab + b² to find 47².
- 16.If a − b = 8 and ab = 9, what is a² + b²?
- 17.Find the value of x² − y² when x = 14 and y = 6.
- 18.Use a² − b² = (a + b)(a − b) to find 57² − 5².
- 19.Use a² − b² = (a + b)(a − b) to find 80² − 69².
- 20.If a + b = 3 and ab = 2, what is a² + b²?
- 21.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 22.Use (a + b)² = a² + 2ab + b² to find 75².
- 23.Find the value of x² + 2xy + y² when x = 8 and y = 1.
- 24.Use (a + b)² = a² + 2ab + b² to find 26².
- 25.Use (a + b)² = a² + 2ab + b² to find 25².
- 26.Use (a − b)² = a² − 2ab + b² to find 26².
- 27.Use (a − b)² = a² − 2ab + b² to find 92².
- 28.If a + b = 14 and ab = 48, what is a² + b²?
- 29.Use (a + b)² = a² + 2ab + b² to find 47².
- 30.Use a² − b² = (a + b)(a − b) to find 43² − 10².
- 31.Use (a − b)² = a² − 2ab + b² to find 17².
- 32.Use (a − b)² = a² − 2ab + b² to find 31².
- 33.Use (a + b)² = a² + 2ab + b² to find 87².
- 34.Use (a + b)² = a² + 2ab + b² to find 86².
- 35.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 36.Use (a − b)² = a² − 2ab + b² to find 87².
- 37.Find the value of x² − 2xy + y² when x = 5 and y = 3.
- 38.If a + b = 20 and ab = 96, what is a² + b²?
- 39.Use (a + b)(a − b) = a² − b² to find 27 × 13.
- 40.Use (a + b)(a − b) = a² − b² to find 95 × 85.
Answer key
- 225
- 13
- 25
- 6241
- 9
- 3969
- 1089
- 841
- 95
- 4225
- 63
- 169
- 3933
- 3721
- 2209
- 82
- 160
- 3224
- 1639
- 5
- 384
- 5625
- 81
- 676
- 625
- 676
- 8464
- 100
- 2209
- 1749
- 289
- 961
- 7569
- 7396
- 884
- 7569
- 4
- 208
- 351
- 8075
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