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 = 9 and y = 5.
- 2.Find the value of x² + 2xy + y² when x = 13 and y = 2.
- 3.Use (a + b)(a − b) = a² − b² to find 79 × 61.
- 4.Find the value of x² − y² when x = 5 and y = 4.
- 5.Find the value of x² − 2xy + y² when x = 15 and y = 8.
- 6.Use (a − b)² = a² − 2ab + b² to find 59².
- 7.Use (a + b)² = a² + 2ab + b² to find 72².
- 8.If a + b = 11 and ab = 24, what is a² + b²?
- 9.If a + b = 8 and ab = 15, what is a² + b²?
- 10.Use (a + b)² = a² + 2ab + b² to find 52².
- 11.Find the value of x² + 2xy + y² when x = 14 and y = 9.
- 12.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 13.If a − b = 1 and ab = 2, what is a² + b²?
- 14.Use a² − b² = (a + b)(a − b) to find 92² − 54².
- 15.Use a² − b² = (a + b)(a − b) to find 71² − 44².
- 16.Use (a − b)² = a² − 2ab + b² to find 65².
- 17.Find the value of x² + 2xy + y² when x = 10 and y = 4.
- 18.If a − b = 1 and ab = 6, what is a² + b²?
- 19.Use a² − b² = (a + b)(a − b) to find 90² − 54².
- 20.Find the value of x² − 2xy + y² when x = 11 and y = 2.
- 21.Use (a + b)(a − b) = a² − b² to find 99 × 81.
- 22.Use (a + b)(a − b) = a² − b² to find 101 × 99.
- 23.Use (a + b)² = a² + 2ab + b² to find 44².
- 24.Use (a + b)² = a² + 2ab + b² to find 102².
- 25.Use a² − b² = (a + b)(a − b) to find 52² − 29².
- 26.Use (a − b)² = a² − 2ab + b² to find 32².
- 27.Use (a − b)² = a² − 2ab + b² to find 75².
- 28.If a + b = 13 and ab = 42, what is a² + b²?
- 29.If a + b = 14 and ab = 24, what is a² + b²?
- 30.If a − b = 6 and ab = 72, what is a² + b²?
- 31.Use a² − b² = (a + b)(a − b) to find 63² − 33².
- 32.Use a² − b² = (a + b)(a − b) to find 33² − 11².
- 33.Use (a + b)² = a² + 2ab + b² to find 89².
- 34.Use a² − b² = (a + b)(a − b) to find 83² − 2².
- 35.Use a² − b² = (a + b)(a − b) to find 49² − 17².
- 36.Find the value of x² − 2xy + y² when x = 12 and y = 4.
- 37.Use (a + b)(a − b) = a² − b² to find 32 × 28.
- 38.Find the value of x² − 2xy + y² when x = 12 and y = 1.
- 39.Use a² − b² = (a + b)(a − b) to find 86² − 75².
- 40.If a + b = 5 and ab = 6, what is a² + b²?
Answer key
- 16
- 225
- 4819
- 9
- 49
- 3481
- 5184
- 73
- 34
- 2704
- 529
- 384
- 5
- 5548
- 3105
- 4225
- 196
- 13
- 5184
- 81
- 8019
- 9999
- 1936
- 10404
- 1863
- 1024
- 5625
- 85
- 148
- 180
- 2880
- 968
- 7921
- 6885
- 2112
- 64
- 896
- 121
- 1771
- 13
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