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 = 7 and ab = 10, what is a² + b²?
- 2.Find the value of x² − 2xy + y² when x = 6 and y = 2.
- 3.Use (a + b)(a − b) = a² − b² to find 86 × 74.
- 4.Use a² − b² = (a + b)(a − b) to find 83² − 71².
- 5.Use (a − b)² = a² − 2ab + b² to find 26².
- 6.Use (a + b)(a − b) = a² − b² to find 84 × 76.
- 7.Use a² − b² = (a + b)(a − b) to find 69² − 48².
- 8.Find the value of x² − 2xy + y² when x = 10 and y = 1.
- 9.Use (a + b)(a − b) = a² − b² to find 45 × 35.
- 10.Use a² − b² = (a + b)(a − b) to find 40² − 9².
- 11.Find the value of x² − y² when x = 10 and y = 9.
- 12.Use (a − b)² = a² − 2ab + b² to find 36².
- 13.If a + b = 7 and ab = 12, what is a² + b²?
- 14.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 15.Use (a + b)² = a² + 2ab + b² to find 14².
- 16.If a + b = 6 and ab = 5, what is a² + b²?
- 17.Use (a + b)² = a² + 2ab + b² to find 18².
- 18.Find the value of x² − 2xy + y² when x = 10 and y = 4.
- 19.Use (a + b)² = a² + 2ab + b² to find 49².
- 20.Use (a − b)² = a² − 2ab + b² to find 48².
- 21.Use (a + b)² = a² + 2ab + b² to find 101².
- 22.Use (a + b)² = a² + 2ab + b² to find 43².
- 23.If a − b = 8 and ab = 33, what is a² + b²?
- 24.Use (a − b)² = a² − 2ab + b² to find 42².
- 25.Use (a + b)² = a² + 2ab + b² to find 37².
- 26.If a − b = 2 and ab = 35, what is a² + b²?
- 27.Use a² − b² = (a + b)(a − b) to find 75² − 24².
- 28.Use (a + b)(a − b) = a² − b² to find 38 × 22.
- 29.Find the value of x² − y² when x = 9 and y = 2.
- 30.If a + b = 13 and ab = 40, what is a² + b²?
- 31.Use a² − b² = (a + b)(a − b) to find 63² − 42².
- 32.Use (a − b)² = a² − 2ab + b² to find 34².
- 33.Use (a + b)² = a² + 2ab + b² to find 34².
- 34.Find the value of x² + 2xy + y² when x = 6 and y = 1.
- 35.Use (a − b)² = a² − 2ab + b² to find 21².
- 36.Find the value of x² + 2xy + y² when x = 6 and y = 3.
- 37.Use (a − b)² = a² − 2ab + b² to find 94².
- 38.Use (a − b)² = a² − 2ab + b² to find 58².
- 39.Use (a + b)² = a² + 2ab + b² to find 71².
- 40.Use a² − b² = (a + b)(a − b) to find 73² − 19².
Answer key
- 29
- 16
- 6364
- 1848
- 676
- 6384
- 2457
- 81
- 1575
- 1519
- 19
- 1296
- 25
- 1591
- 196
- 26
- 324
- 36
- 2401
- 2304
- 10201
- 1849
- 130
- 1764
- 1369
- 74
- 5049
- 836
- 77
- 89
- 2205
- 1156
- 1156
- 49
- 441
- 81
- 8836
- 3364
- 5041
- 4968
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