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 = 4 and ab = 5, what is a² + b²?
- 2.Use (a + b)(a − b) = a² − b² to find 48 × 32.
- 3.Use (a + b)² = a² + 2ab + b² to find 44².
- 4.Use (a + b)(a − b) = a² − b² to find 59 × 41.
- 5.Use a² − b² = (a + b)(a − b) to find 36² − 20².
- 6.If a − b = 4 and ab = 45, what is a² + b²?
- 7.Use (a − b)² = a² − 2ab + b² to find 98².
- 8.Use (a + b)(a − b) = a² − b² to find 79 × 61.
- 9.Find the value of x² − 2xy + y² when x = 3 and y = 1.
- 10.Find the value of x² − 2xy + y² when x = 12 and y = 3.
- 11.Use (a + b)² = a² + 2ab + b² to find 81².
- 12.Find the value of x² − y² when x = 9 and y = 4.
- 13.Use (a + b)² = a² + 2ab + b² to find 53².
- 14.If a + b = 6 and ab = 8, what is a² + b²?
- 15.Use a² − b² = (a + b)(a − b) to find 68² − 54².
- 16.Use a² − b² = (a + b)(a − b) to find 55² − 49².
- 17.If a − b = 2 and ab = 24, what is a² + b²?
- 18.If a − b = 3 and ab = 4, what is a² + b²?
- 19.Find the value of x² + 2xy + y² when x = 14 and y = 6.
- 20.If a + b = 5 and ab = 6, what is a² + b²?
- 21.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 22.Use a² − b² = (a + b)(a − b) to find 63² − 43².
- 23.Find the value of x² + 2xy + y² when x = 8 and y = 5.
- 24.Use a² − b² = (a + b)(a − b) to find 39² − 26².
- 25.Use (a − b)² = a² − 2ab + b² to find 57².
- 26.Use (a − b)² = a² − 2ab + b² to find 91².
- 27.Use (a − b)² = a² − 2ab + b² to find 64².
- 28.Use (a + b)² = a² + 2ab + b² to find 86².
- 29.Use a² − b² = (a + b)(a − b) to find 72² − 54².
- 30.Use (a − b)² = a² − 2ab + b² to find 63².
- 31.If a + b = 10 and ab = 21, what is a² + b²?
- 32.Use a² − b² = (a + b)(a − b) to find 29² − 26².
- 33.Use (a − b)² = a² − 2ab + b² to find 34².
- 34.Use (a + b)² = a² + 2ab + b² to find 18².
- 35.Use a² − b² = (a + b)(a − b) to find 36² − 29².
- 36.Use (a − b)² = a² − 2ab + b² to find 88².
- 37.If a + b = 13 and ab = 36, what is a² + b²?
- 38.Use (a + b)² = a² + 2ab + b² to find 84².
- 39.If a − b = 1 and ab = 2, what is a² + b²?
- 40.Use (a + b)² = a² + 2ab + b² to find 95².
Answer key
- 26
- 1536
- 1936
- 2419
- 896
- 106
- 9604
- 4819
- 4
- 81
- 6561
- 65
- 2809
- 20
- 1708
- 624
- 52
- 17
- 400
- 13
- 875
- 2120
- 169
- 845
- 3249
- 8281
- 4096
- 7396
- 2268
- 3969
- 58
- 165
- 1156
- 324
- 455
- 7744
- 97
- 7056
- 5
- 9025
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