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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 552 · 40 sums
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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.

NameDateTime takenScore ___ / 40
  1. 1.Use a² − b² = (a + b)(a − b) to find 40² − 1².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 42².
  3. 3.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  4. 4.If a + b = 7 and ab = 10, what is a² + b²?
  5. 5.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  6. 6.If a − b = 3 and ab = 40, what is a² + b²?
  7. 7.If a − b = 2 and ab = 8, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 19².
  9. 9.Use a² − b² = (a + b)(a − b) to find 35² − 28².
  10. 10.Find the value of x² + 2xy + y² when x = 15 and y = 2.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 88².
  12. 12.Find the value of x² − y² when x = 13 and y = 9.
  13. 13.If a − b = 1 and ab = 12, what is a² + b²?
  14. 14.Use a² − b² = (a + b)(a − b) to find 98² − 80².
  15. 15.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 49².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 24².
  18. 18.Find the value of x² − 2xy + y² when x = 7 and y = 1.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 11².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 67².
  21. 21.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  22. 22.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  23. 23.If a − b = 4 and ab = 12, what is a² + b²?
  24. 24.Use (a − b)² = a² − 2ab + b² to find 95².
  25. 25.If a − b = 1 and ab = 6, what is a² + b²?
  26. 26.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  27. 27.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  28. 28.Find the value of x² − 2xy + y² when x = 13 and y = 10.
  29. 29.If a − b = 3 and ab = 108, what is a² + b²?
  30. 30.Use (a − b)² = a² − 2ab + b² to find 93².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 102².
  32. 32.Use a² − b² = (a + b)(a − b) to find 59² − 48².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 52².
  34. 34.If a − b = 1 and ab = 110, what is a² + b²?
  35. 35.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 21².
  37. 37.Use a² − b² = (a + b)(a − b) to find 91² − 16².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 92².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 38².
  40. 40.Find the value of x² − 2xy + y² when x = 7 and y = 6.

Answer key

  1. 1599
  2. 1764
  3. 9975
  4. 29
  5. 875
  6. 89
  7. 20
  8. 361
  9. 441
  10. 289
  11. 7744
  12. 88
  13. 25
  14. 3204
  15. 8084
  16. 2401
  17. 576
  18. 36
  19. 121
  20. 4489
  21. 1596
  22. 9964
  23. 40
  24. 9025
  25. 13
  26. 3596
  27. 8064
  28. 9
  29. 225
  30. 8649
  31. 10404
  32. 1177
  33. 2704
  34. 221
  35. 2475
  36. 441
  37. 8025
  38. 8464
  39. 1444
  40. 1

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