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.Use (a − b)² = a² − 2ab + b² to find 83².
- 2.Find the value of x² − y² when x = 10 and y = 2.
- 3.Use (a − b)² = a² − 2ab + b² to find 73².
- 4.Use (a + b)(a − b) = a² − b² to find 48 × 32.
- 5.Use (a − b)² = a² − 2ab + b² to find 97².
- 6.Use (a + b)² = a² + 2ab + b² to find 57².
- 7.Use (a − b)² = a² − 2ab + b² to find 72².
- 8.If a + b = 10 and ab = 9, what is a² + b²?
- 9.Use (a + b)² = a² + 2ab + b² to find 82².
- 10.If a + b = 18 and ab = 77, what is a² + b²?
- 11.Find the value of x² + 2xy + y² when x = 4 and y = 3.
- 12.Use a² − b² = (a + b)(a − b) to find 23² − 8².
- 13.Use (a − b)² = a² − 2ab + b² to find 27².
- 14.Use (a + b)² = a² + 2ab + b² to find 91².
- 15.Use (a + b)² = a² + 2ab + b² to find 32².
- 16.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 17.Use (a + b)² = a² + 2ab + b² to find 94².
- 18.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 19.Use (a + b)² = a² + 2ab + b² to find 37².
- 20.Use (a + b)² = a² + 2ab + b² to find 41².
- 21.Use (a + b)² = a² + 2ab + b² to find 76².
- 22.Use (a − b)² = a² − 2ab + b² to find 18².
- 23.Use (a + b)² = a² + 2ab + b² to find 97².
- 24.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 25.If a + b = 20 and ab = 99, what is a² + b²?
- 26.Use a² − b² = (a + b)(a − b) to find 54² − 44².
- 27.Use (a + b)² = a² + 2ab + b² to find 64².
- 28.Use a² − b² = (a + b)(a − b) to find 27² − 20².
- 29.Find the value of x² + 2xy + y² when x = 4 and y = 2.
- 30.Use (a + b)² = a² + 2ab + b² to find 12².
- 31.Use (a + b)(a − b) = a² − b² to find 105 × 95.
- 32.Use a² − b² = (a + b)(a − b) to find 54² − 29².
- 33.If a − b = 1 and ab = 6, what is a² + b²?
- 34.Find the value of x² − 2xy + y² when x = 5 and y = 1.
- 35.If a − b = 3 and ab = 18, what is a² + b²?
- 36.If a + b = 13 and ab = 36, what is a² + b²?
- 37.Use (a + b)² = a² + 2ab + b² to find 46².
- 38.Use (a − b)² = a² − 2ab + b² to find 45².
- 39.Use (a + b)(a − b) = a² − b² to find 91 × 89.
- 40.If a − b = 4 and ab = 45, what is a² + b²?
Answer key
- 6889
- 96
- 5329
- 1536
- 9409
- 3249
- 5184
- 82
- 6724
- 170
- 49
- 465
- 729
- 8281
- 1024
- 1591
- 8836
- 4899
- 1369
- 1681
- 5776
- 324
- 9409
- 8091
- 202
- 980
- 4096
- 329
- 36
- 144
- 9975
- 2075
- 13
- 16
- 45
- 97
- 2116
- 2025
- 8099
- 106
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