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 = 5 and ab = 4, what is a² + b²?
- 2.Find the value of x² + 2xy + y² when x = 6 and y = 5.
- 3.Use a² − b² = (a + b)(a − b) to find 93² − 63².
- 4.Use (a + b)² = a² + 2ab + b² to find 52².
- 5.Use (a − b)² = a² − 2ab + b² to find 24².
- 6.Use (a − b)² = a² − 2ab + b² to find 41².
- 7.If a + b = 10 and ab = 21, what is a² + b²?
- 8.Find the value of x² − y² when x = 12 and y = 9.
- 9.Use (a − b)² = a² − 2ab + b² to find 57².
- 10.If a + b = 3 and ab = 2, what is a² + b²?
- 11.Use (a + b)² = a² + 2ab + b² to find 63².
- 12.Use a² − b² = (a + b)(a − b) to find 45² − 35².
- 13.Use a² − b² = (a + b)(a − b) to find 82² − 53².
- 14.If a + b = 15 and ab = 44, what is a² + b²?
- 15.Use (a − b)² = a² − 2ab + b² to find 83².
- 16.Use (a + b)² = a² + 2ab + b² to find 27².
- 17.If a + b = 14 and ab = 33, what is a² + b²?
- 18.Use (a + b)(a − b) = a² − b² to find 73 × 67.
- 19.Use a² − b² = (a + b)(a − b) to find 28² − 5².
- 20.Use (a − b)² = a² − 2ab + b² to find 73².
- 21.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 22.Use (a + b)(a − b) = a² − b² to find 22 × 18.
- 23.Use (a + b)² = a² + 2ab + b² to find 34².
- 24.Use a² − b² = (a + b)(a − b) to find 41² − 16².
- 25.Use (a − b)² = a² − 2ab + b² to find 62².
- 26.Find the value of x² − y² when x = 6 and y = 5.
- 27.Use (a + b)² = a² + 2ab + b² to find 49².
- 28.If a + b = 13 and ab = 12, what is a² + b²?
- 29.Use (a + b)(a − b) = a² − b² to find 31 × 29.
- 30.Use (a − b)² = a² − 2ab + b² to find 78².
- 31.Use (a + b)(a − b) = a² − b² to find 39 × 21.
- 32.Use a² − b² = (a + b)(a − b) to find 51² − 46².
- 33.Use (a + b)(a − b) = a² − b² to find 27 × 13.
- 34.Use (a + b)² = a² + 2ab + b² to find 43².
- 35.Use a² − b² = (a + b)(a − b) to find 31² − 18².
- 36.Use (a + b)² = a² + 2ab + b² to find 67².
- 37.Use a² − b² = (a + b)(a − b) to find 25² − 21².
- 38.Use (a − b)² = a² − 2ab + b² to find 13².
- 39.Use (a + b)(a − b) = a² − b² to find 94 × 86.
- 40.Use (a + b)² = a² + 2ab + b² to find 82².
Answer key
- 17
- 121
- 4680
- 2704
- 576
- 1681
- 58
- 63
- 3249
- 5
- 3969
- 800
- 3915
- 137
- 6889
- 729
- 130
- 4891
- 759
- 5329
- 864
- 396
- 1156
- 1425
- 3844
- 11
- 2401
- 145
- 899
- 6084
- 819
- 485
- 351
- 1849
- 637
- 4489
- 184
- 169
- 8084
- 6724
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