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 − y² when x = 11 and y = 1.
- 2.Use a² − b² = (a + b)(a − b) to find 83² − 64².
- 3.Find the value of x² − y² when x = 3 and y = 2.
- 4.Use (a + b)² = a² + 2ab + b² to find 36².
- 5.Use (a − b)² = a² − 2ab + b² to find 17².
- 6.Use a² − b² = (a + b)(a − b) to find 60² − 44².
- 7.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 8.If a + b = 4 and ab = 3, what is a² + b²?
- 9.If a + b = 15 and ab = 44, what is a² + b²?
- 10.Find the value of x² − 2xy + y² when x = 10 and y = 8.
- 11.Use a² − b² = (a + b)(a − b) to find 63² − 46².
- 12.If a + b = 10 and ab = 24, what is a² + b²?
- 13.Find the value of x² + 2xy + y² when x = 12 and y = 10.
- 14.Find the value of x² − 2xy + y² when x = 12 and y = 4.
- 15.Use (a − b)² = a² − 2ab + b² to find 19².
- 16.Use a² − b² = (a + b)(a − b) to find 27² − 13².
- 17.Use a² − b² = (a + b)(a − b) to find 88² − 42².
- 18.If a − b = 1 and ab = 72, what is a² + b²?
- 19.Use (a − b)² = a² − 2ab + b² to find 91².
- 20.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 21.Use (a + b)(a − b) = a² − b² to find 57 × 43.
- 22.Use a² − b² = (a + b)(a − b) to find 45² − 39².
- 23.If a + b = 5 and ab = 4, what is a² + b²?
- 24.Use (a + b)(a − b) = a² − b² to find 77 × 63.
- 25.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 26.Find the value of x² + 2xy + y² when x = 7 and y = 1.
- 27.Use (a − b)² = a² − 2ab + b² to find 22².
- 28.If a − b = 5 and ab = 84, what is a² + b²?
- 29.Use a² − b² = (a + b)(a − b) to find 34² − 18².
- 30.Use (a + b)² = a² + 2ab + b² to find 28².
- 31.If a − b = 5 and ab = 6, what is a² + b²?
- 32.If a + b = 10 and ab = 21, what is a² + b²?
- 33.Use (a + b)² = a² + 2ab + b² to find 83².
- 34.Use (a − b)² = a² − 2ab + b² to find 16².
- 35.Use (a + b)(a − b) = a² − b² to find 25 × 15.
- 36.Use (a − b)² = a² − 2ab + b² to find 87².
- 37.Use (a + b)(a − b) = a² − b² to find 48 × 32.
- 38.Use (a − b)² = a² − 2ab + b² to find 81².
- 39.Use a² − b² = (a + b)(a − b) to find 52² − 25².
- 40.Use (a − b)² = a² − 2ab + b² to find 57².
Answer key
- 120
- 2793
- 5
- 1296
- 289
- 1664
- 399
- 10
- 137
- 4
- 1853
- 52
- 484
- 64
- 361
- 560
- 5980
- 145
- 8281
- 4896
- 2451
- 504
- 17
- 4851
- 875
- 64
- 484
- 193
- 832
- 784
- 37
- 58
- 6889
- 256
- 375
- 7569
- 1536
- 6561
- 2079
- 3249
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