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 27².
- 2.If a − b = 3 and ab = 4, what is a² + b²?
- 3.Find the value of x² − y² when x = 14 and y = 11.
- 4.Use (a − b)² = a² − 2ab + b² to find 17².
- 5.Find the value of x² − y² when x = 7 and y = 6.
- 6.Use (a − b)² = a² − 2ab + b² to find 37².
- 7.Use (a + b)(a − b) = a² − b² to find 22 × 18.
- 8.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 9.Find the value of x² − y² when x = 13 and y = 9.
- 10.Use (a − b)² = a² − 2ab + b² to find 73².
- 11.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 12.If a − b = 9 and ab = 22, what is a² + b²?
- 13.Use (a − b)² = a² − 2ab + b² to find 12².
- 14.Use a² − b² = (a + b)(a − b) to find 87² − 28².
- 15.If a + b = 13 and ab = 42, what is a² + b²?
- 16.Use (a − b)² = a² − 2ab + b² to find 59².
- 17.Use a² − b² = (a + b)(a − b) to find 42² − 33².
- 18.Use a² − b² = (a + b)(a − b) to find 62² − 29².
- 19.Use (a + b)² = a² + 2ab + b² to find 37².
- 20.Use (a − b)² = a² − 2ab + b² to find 23².
- 21.Use a² − b² = (a + b)(a − b) to find 84² − 83².
- 22.Use a² − b² = (a + b)(a − b) to find 95² − 70².
- 23.Use a² − b² = (a + b)(a − b) to find 69² − 42².
- 24.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 25.Use (a + b)² = a² + 2ab + b² to find 32².
- 26.Use (a − b)² = a² − 2ab + b² to find 55².
- 27.If a + b = 17 and ab = 72, what is a² + b²?
- 28.Find the value of x² + 2xy + y² when x = 6 and y = 1.
- 29.If a + b = 10 and ab = 21, what is a² + b²?
- 30.If a + b = 21 and ab = 108, what is a² + b²?
- 31.Use (a − b)² = a² − 2ab + b² to find 45².
- 32.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 33.Use a² − b² = (a + b)(a − b) to find 63² − 29².
- 34.Use a² − b² = (a + b)(a − b) to find 89² − 1².
- 35.Use a² − b² = (a + b)(a − b) to find 69² − 26².
- 36.Find the value of x² − 2xy + y² when x = 11 and y = 6.
- 37.Use a² − b² = (a + b)(a − b) to find 27² − 2².
- 38.If a − b = 3 and ab = 10, what is a² + b²?
- 39.Find the value of x² + 2xy + y² when x = 11 and y = 2.
- 40.Use (a − b)² = a² − 2ab + b² to find 22².
Answer key
- 729
- 17
- 75
- 289
- 13
- 1369
- 396
- 391
- 88
- 5329
- 4896
- 125
- 144
- 6785
- 85
- 3481
- 675
- 3003
- 1369
- 529
- 167
- 4125
- 2997
- 864
- 1024
- 3025
- 145
- 49
- 58
- 225
- 2025
- 1551
- 3128
- 7920
- 4085
- 25
- 725
- 29
- 169
- 484
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