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 = 15 and ab = 36, what is a² + b²?
- 2.Use (a − b)² = a² − 2ab + b² to find 75².
- 3.Find the value of x² − y² when x = 10 and y = 1.
- 4.Use (a − b)² = a² − 2ab + b² to find 35².
- 5.Find the value of x² + 2xy + y² when x = 14 and y = 13.
- 6.Use a² − b² = (a + b)(a − b) to find 98² − 43².
- 7.Use a² − b² = (a + b)(a − b) to find 88² − 17².
- 8.Find the value of x² − y² when x = 10 and y = 9.
- 9.If a + b = 6 and ab = 5, what is a² + b²?
- 10.Use a² − b² = (a + b)(a − b) to find 42² − 16².
- 11.Use (a + b)(a − b) = a² − b² to find 49 × 31.
- 12.Find the value of x² + 2xy + y² when x = 13 and y = 11.
- 13.Use (a + b)(a − b) = a² − b² to find 98 × 82.
- 14.Use (a + b)(a − b) = a² − b² to find 41 × 39.
- 15.Find the value of x² − 2xy + y² when x = 4 and y = 2.
- 16.Use (a + b)² = a² + 2ab + b² to find 33².
- 17.Find the value of x² + 2xy + y² when x = 15 and y = 1.
- 18.Use (a − b)² = a² − 2ab + b² to find 16².
- 19.Find the value of x² − y² when x = 5 and y = 3.
- 20.Use (a + b)(a − b) = a² − b² to find 42 × 38.
- 21.Use (a + b)² = a² + 2ab + b² to find 108².
- 22.Use a² − b² = (a + b)(a − b) to find 96² − 10².
- 23.If a − b = 5 and ab = 36, what is a² + b²?
- 24.Use a² − b² = (a + b)(a − b) to find 94² − 11².
- 25.Use (a + b)(a − b) = a² − b² to find 95 × 85.
- 26.Use (a + b)² = a² + 2ab + b² to find 37².
- 27.Use (a + b)² = a² + 2ab + b² to find 15².
- 28.Use (a + b)² = a² + 2ab + b² to find 35².
- 29.Use (a − b)² = a² − 2ab + b² to find 34².
- 30.Use a² − b² = (a + b)(a − b) to find 93² − 55².
- 31.Use (a + b)² = a² + 2ab + b² to find 82².
- 32.Use (a − b)² = a² − 2ab + b² to find 53².
- 33.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 34.If a − b = 2 and ab = 8, what is a² + b²?
- 35.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 36.Use (a − b)² = a² − 2ab + b² to find 61².
- 37.If a − b = 8 and ab = 20, what is a² + b²?
- 38.Use (a − b)² = a² − 2ab + b² to find 82².
- 39.Use a² − b² = (a + b)(a − b) to find 29² − 9².
- 40.Use (a − b)² = a² − 2ab + b² to find 28².
Answer key
- 153
- 5625
- 99
- 1225
- 729
- 7755
- 7455
- 19
- 26
- 1508
- 1519
- 576
- 8036
- 1599
- 4
- 1089
- 256
- 256
- 16
- 1596
- 11664
- 9116
- 97
- 8715
- 8075
- 1369
- 225
- 1225
- 1156
- 5624
- 6724
- 2809
- 884
- 20
- 4899
- 3721
- 104
- 6724
- 760
- 784
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