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.If a + b = 6 and ab = 8, what is a² + b²?
- 2.Use a² − b² = (a + b)(a − b) to find 44² − 29².
- 3.Use a² − b² = (a + b)(a − b) to find 81² − 42².
- 4.Find the value of x² + 2xy + y² when x = 15 and y = 7.
- 5.Use (a + b)² = a² + 2ab + b² to find 26².
- 6.Use a² − b² = (a + b)(a − b) to find 39² − 31².
- 7.Use (a − b)² = a² − 2ab + b² to find 11².
- 8.Use (a + b)² = a² + 2ab + b² to find 101².
- 9.If a + b = 6 and ab = 5, what is a² + b²?
- 10.Use (a + b)² = a² + 2ab + b² to find 61².
- 11.Use (a − b)² = a² − 2ab + b² to find 29².
- 12.Use (a + b)² = a² + 2ab + b² to find 13².
- 13.Use (a + b)(a − b) = a² − b² to find 67 × 53.
- 14.Find the value of x² − 2xy + y² when x = 13 and y = 6.
- 15.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 16.If a + b = 11 and ab = 28, what is a² + b²?
- 17.Use (a − b)² = a² − 2ab + b² to find 77².
- 18.Use (a + b)(a − b) = a² − b² to find 85 × 75.
- 19.Use (a − b)² = a² − 2ab + b² to find 98².
- 20.If a + b = 5 and ab = 4, what is a² + b²?
- 21.Use (a − b)² = a² − 2ab + b² to find 17².
- 22.Use (a − b)² = a² − 2ab + b² to find 79².
- 23.Find the value of x² − y² when x = 6 and y = 5.
- 24.Use (a + b)² = a² + 2ab + b² to find 42².
- 25.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 26.Use (a − b)² = a² − 2ab + b² to find 28².
- 27.Find the value of x² − 2xy + y² when x = 4 and y = 3.
- 28.If a + b = 10 and ab = 9, what is a² + b²?
- 29.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 30.Use (a + b)² = a² + 2ab + b² to find 49².
- 31.Use (a − b)² = a² − 2ab + b² to find 36².
- 32.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 33.If a + b = 19 and ab = 84, what is a² + b²?
- 34.Use a² − b² = (a + b)(a − b) to find 59² − 10².
- 35.If a + b = 8 and ab = 7, what is a² + b²?
- 36.Use (a + b)² = a² + 2ab + b² to find 12².
- 37.Use (a + b)(a − b) = a² − b² to find 101 × 99.
- 38.Find the value of x² + 2xy + y² when x = 10 and y = 6.
- 39.Use (a + b)² = a² + 2ab + b² to find 54².
- 40.Use (a + b)² = a² + 2ab + b² to find 32².
Answer key
- 20
- 1095
- 4797
- 484
- 676
- 560
- 121
- 10201
- 26
- 3721
- 841
- 169
- 3551
- 49
- 884
- 65
- 5929
- 6375
- 9604
- 17
- 289
- 6241
- 11
- 1764
- 8091
- 784
- 1
- 82
- 4896
- 2401
- 1296
- 3596
- 193
- 3381
- 50
- 144
- 9999
- 256
- 2916
- 1024
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