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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 387 · 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 (a − b)² = a² − 2ab + b² to find 68².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 82².
  3. 3.If a − b = 1 and ab = 6, what is a² + b²?
  4. 4.If a + b = 6 and ab = 8, what is a² + b²?
  5. 5.Use a² − b² = (a + b)(a − b) to find 79² − 46².
  6. 6.If a − b = 1 and ab = 2, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 45².
  8. 8.Use a² − b² = (a + b)(a − b) to find 81² − 17².
  9. 9.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  10. 10.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  11. 11.Find the value of x² + 2xy + y² when x = 14 and y = 5.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 17².
  13. 13.Find the value of x² − y² when x = 11 and y = 10.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 94².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 94².
  16. 16.If a + b = 16 and ab = 48, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 58².
  18. 18.If a + b = 9 and ab = 20, what is a² + b²?
  19. 19.Find the value of x² + 2xy + y² when x = 11 and y = 9.
  20. 20.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  21. 21.If a + b = 12 and ab = 32, what is a² + b²?
  22. 22.Use (a + b)² = a² + 2ab + b² to find 14².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 49².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 102².
  25. 25.Find the value of x² + 2xy + y² when x = 9 and y = 2.
  26. 26.Find the value of x² − y² when x = 6 and y = 5.
  27. 27.Use a² − b² = (a + b)(a − b) to find 23² − 10².
  28. 28.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 48².
  30. 30.Use a² − b² = (a + b)(a − b) to find 34² − 23².
  31. 31.Use a² − b² = (a + b)(a − b) to find 94² − 56².
  32. 32.Use a² − b² = (a + b)(a − b) to find 21² − 16².
  33. 33.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  34. 34.Use a² − b² = (a + b)(a − b) to find 97² − 71².
  35. 35.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 46².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 26².
  38. 38.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  39. 39.Find the value of x² + 2xy + y² when x = 11 and y = 7.
  40. 40.Find the value of x² + 2xy + y² when x = 10 and y = 7.

Answer key

  1. 4624
  2. 6724
  3. 13
  4. 20
  5. 4125
  6. 5
  7. 2025
  8. 6272
  9. 6384
  10. 9984
  11. 361
  12. 289
  13. 21
  14. 8836
  15. 8836
  16. 160
  17. 3364
  18. 41
  19. 400
  20. 81
  21. 80
  22. 196
  23. 2401
  24. 10404
  25. 121
  26. 11
  27. 429
  28. 2436
  29. 2304
  30. 627
  31. 5700
  32. 185
  33. 864
  34. 4368
  35. 144
  36. 2116
  37. 676
  38. 4896
  39. 324
  40. 289

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