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 73².
- 3.Use (a + b)² = a² + 2ab + b² to find 41².
- 4.Use a² − b² = (a + b)(a − b) to find 54² − 7².
- 5.Use (a + b)² = a² + 2ab + b² to find 79².
- 6.Use (a − b)² = a² − 2ab + b² to find 22².
- 7.Use (a − b)² = a² − 2ab + b² to find 34².
- 8.Use (a − b)² = a² − 2ab + b² to find 36².
- 9.Use (a + b)² = a² + 2ab + b² to find 108².
- 10.If a + b = 5 and ab = 4, what is a² + b²?
- 11.Use (a + b)² = a² + 2ab + b² to find 102².
- 12.Use a² − b² = (a + b)(a − b) to find 69² − 20².
- 13.Use (a + b)² = a² + 2ab + b² to find 84².
- 14.Use (a − b)² = a² − 2ab + b² to find 49².
- 15.Use (a − b)² = a² − 2ab + b² to find 35².
- 16.Use (a + b)² = a² + 2ab + b² to find 26².
- 17.Find the value of x² + 2xy + y² when x = 14 and y = 6.
- 18.Find the value of x² − 2xy + y² when x = 3 and y = 2.
- 19.Use (a + b)(a − b) = a² − b² to find 51 × 49.
- 20.Find the value of x² + 2xy + y² when x = 8 and y = 6.
- 21.Use (a + b)(a − b) = a² − b² to find 33 × 27.
- 22.If a + b = 22 and ab = 120, what is a² + b²?
- 23.Use (a + b)(a − b) = a² − b² to find 99 × 81.
- 24.Use (a + b)² = a² + 2ab + b² to find 54².
- 25.Find the value of x² − 2xy + y² when x = 10 and y = 8.
- 26.If a + b = 15 and ab = 54, what is a² + b²?
- 27.If a − b = 2 and ab = 8, what is a² + b²?
- 28.Use a² − b² = (a + b)(a − b) to find 33² − 6².
- 29.Use (a + b)² = a² + 2ab + b² to find 24².
- 30.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 31.Use a² − b² = (a + b)(a − b) to find 88² − 10².
- 32.Use (a − b)² = a² − 2ab + b² to find 24².
- 33.Find the value of x² − y² when x = 5 and y = 2.
- 34.If a − b = 8 and ab = 9, what is a² + b²?
- 35.Use (a + b)(a − b) = a² − b² to find 75 × 65.
- 36.If a − b = 1 and ab = 6, what is a² + b²?
- 37.Find the value of x² − 2xy + y² when x = 7 and y = 1.
- 38.Use (a − b)² = a² − 2ab + b² to find 65².
- 39.Use (a + b)² = a² + 2ab + b² to find 36².
- 40.Find the value of x² − 2xy + y² when x = 11 and y = 3.
Answer key
- 153
- 5329
- 1681
- 2867
- 6241
- 484
- 1156
- 1296
- 11664
- 17
- 10404
- 4361
- 7056
- 2401
- 1225
- 676
- 400
- 1
- 2499
- 196
- 891
- 244
- 8019
- 2916
- 4
- 117
- 20
- 1053
- 576
- 3596
- 7644
- 576
- 21
- 82
- 4875
- 13
- 36
- 4225
- 1296
- 64
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