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 a² − b² = (a + b)(a − b) to find 92² − 75².
- 2.Find the value of x² + 2xy + y² when x = 10 and y = 6.
- 3.If a + b = 3 and ab = 2, what is a² + b²?
- 4.Use (a + b)² = a² + 2ab + b² to find 67².
- 5.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 6.Use (a + b)(a − b) = a² − b² to find 106 × 94.
- 7.Use a² − b² = (a + b)(a − b) to find 39² − 32².
- 8.If a − b = 1 and ab = 72, what is a² + b²?
- 9.Use (a − b)² = a² − 2ab + b² to find 55².
- 10.Use (a − b)² = a² − 2ab + b² to find 11².
- 11.Find the value of x² − y² when x = 5 and y = 3.
- 12.Use a² − b² = (a + b)(a − b) to find 42² − 32².
- 13.If a + b = 7 and ab = 12, what is a² + b²?
- 14.Use (a + b)² = a² + 2ab + b² to find 91².
- 15.If a + b = 13 and ab = 42, what is a² + b²?
- 16.Use (a + b)(a − b) = a² − b² to find 95 × 85.
- 17.Use (a + b)² = a² + 2ab + b² to find 78².
- 18.Use (a + b)² = a² + 2ab + b² to find 65².
- 19.If a + b = 9 and ab = 8, what is a² + b²?
- 20.Use a² − b² = (a + b)(a − b) to find 50² − 15².
- 21.Find the value of x² + 2xy + y² when x = 13 and y = 3.
- 22.Find the value of x² − y² when x = 8 and y = 1.
- 23.Use (a + b)(a − b) = a² − b² to find 37 × 23.
- 24.Use (a + b)(a − b) = a² − b² to find 56 × 44.
- 25.Use (a + b)(a − b) = a² − b² to find 51 × 49.
- 26.Use (a + b)² = a² + 2ab + b² to find 42².
- 27.Find the value of x² − 2xy + y² when x = 3 and y = 2.
- 28.Use (a + b)(a − b) = a² − b² to find 65 × 55.
- 29.Use a² − b² = (a + b)(a − b) to find 86² − 82².
- 30.If a − b = 1 and ab = 132, what is a² + b²?
- 31.Use (a + b)² = a² + 2ab + b² to find 81².
- 32.If a − b = 4 and ab = 60, what is a² + b²?
- 33.Use (a − b)² = a² − 2ab + b² to find 35².
- 34.Use (a + b)² = a² + 2ab + b² to find 58².
- 35.Use (a − b)² = a² − 2ab + b² to find 52².
- 36.If a + b = 5 and ab = 6, what is a² + b²?
- 37.If a + b = 17 and ab = 72, what is a² + b²?
- 38.Use (a − b)² = a² − 2ab + b² to find 19².
- 39.Use (a − b)² = a² − 2ab + b² to find 12².
- 40.Use (a + b)² = a² + 2ab + b² to find 16².
Answer key
- 2839
- 256
- 5
- 4489
- 4899
- 9964
- 497
- 145
- 3025
- 121
- 16
- 740
- 25
- 8281
- 85
- 8075
- 6084
- 4225
- 65
- 2275
- 256
- 63
- 851
- 2464
- 2499
- 1764
- 1
- 3575
- 672
- 265
- 6561
- 136
- 1225
- 3364
- 2704
- 13
- 145
- 361
- 144
- 256
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