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 = 10 and y = 3.
- 2.Use (a + b)² = a² + 2ab + b² to find 49².
- 3.Find the value of x² + 2xy + y² when x = 14 and y = 3.
- 4.If a − b = 5 and ab = 36, what is a² + b²?
- 5.Use (a + b)² = a² + 2ab + b² to find 27².
- 6.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 7.Use (a + b)(a − b) = a² − b² to find 32 × 28.
- 8.Use (a + b)² = a² + 2ab + b² to find 93².
- 9.Use (a − b)² = a² − 2ab + b² to find 12².
- 10.Use (a − b)² = a² − 2ab + b² to find 53².
- 11.Use (a + b)² = a² + 2ab + b² to find 74².
- 12.Use (a + b)(a − b) = a² − b² to find 98 × 82.
- 13.If a − b = 3 and ab = 88, what is a² + b²?
- 14.Find the value of x² + 2xy + y² when x = 5 and y = 1.
- 15.Use (a + b)(a − b) = a² − b² to find 45 × 35.
- 16.Use (a + b)² = a² + 2ab + b² to find 72².
- 17.Find the value of x² + 2xy + y² when x = 6 and y = 1.
- 18.Use (a + b)² = a² + 2ab + b² to find 101².
- 19.Use a² − b² = (a + b)(a − b) to find 23² − 22².
- 20.Use (a + b)(a − b) = a² − b² to find 82 × 78.
- 21.Find the value of x² − y² when x = 9 and y = 8.
- 22.Use a² − b² = (a + b)(a − b) to find 20² − 19².
- 23.Use (a + b)² = a² + 2ab + b² to find 98².
- 24.Use (a − b)² = a² − 2ab + b² to find 19².
- 25.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 26.Find the value of x² + 2xy + y² when x = 11 and y = 2.
- 27.Use (a + b)² = a² + 2ab + b² to find 35².
- 28.Use (a − b)² = a² − 2ab + b² to find 85².
- 29.If a + b = 6 and ab = 8, what is a² + b²?
- 30.Use a² − b² = (a + b)(a − b) to find 89² − 7².
- 31.Use (a + b)(a − b) = a² − b² to find 69 × 51.
- 32.Find the value of x² − y² when x = 15 and y = 13.
- 33.Use (a + b)² = a² + 2ab + b² to find 41².
- 34.Use (a + b)² = a² + 2ab + b² to find 68².
- 35.Use (a + b)(a − b) = a² − b² to find 57 × 43.
- 36.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 37.Use (a + b)² = a² + 2ab + b² to find 28².
- 38.Find the value of x² + 2xy + y² when x = 11 and y = 1.
- 39.Use a² − b² = (a + b)(a − b) to find 77² − 29².
- 40.Find the value of x² + 2xy + y² when x = 15 and y = 4.
Answer key
- 169
- 2401
- 289
- 97
- 729
- 25
- 896
- 8649
- 144
- 2809
- 5476
- 8036
- 185
- 36
- 1575
- 5184
- 49
- 10201
- 45
- 6396
- 17
- 39
- 9604
- 361
- 3591
- 169
- 1225
- 7225
- 20
- 7872
- 3519
- 56
- 1681
- 4624
- 2451
- 399
- 784
- 144
- 5088
- 361
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