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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 187 · 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 97².
  2. 2.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  3. 3.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 71².
  5. 5.Find the value of x² − y² when x = 9 and y = 3.
  6. 6.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  7. 7.If a − b = 2 and ab = 24, what is a² + b²?
  8. 8.Use a² − b² = (a + b)(a − b) to find 22² − 17².
  9. 9.If a − b = 1 and ab = 2, what is a² + b²?
  10. 10.If a − b = 1 and ab = 12, what is a² + b²?
  11. 11.Find the value of x² − y² when x = 11 and y = 9.
  12. 12.If a − b = 4 and ab = 12, what is a² + b²?
  13. 13.Use a² − b² = (a + b)(a − b) to find 28² − 25².
  14. 14.If a − b = 2 and ab = 3, what is a² + b²?
  15. 15.Use (a − b)² = a² − 2ab + b² to find 25².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 36².
  17. 17.Use a² − b² = (a + b)(a − b) to find 31² − 25².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 46².
  19. 19.Find the value of x² + 2xy + y² when x = 15 and y = 1.
  20. 20.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  21. 21.If a − b = 10 and ab = 24, what is a² + b²?
  22. 22.Use (a − b)² = a² − 2ab + b² to find 63².
  23. 23.Use a² − b² = (a + b)(a − b) to find 47² − 12².
  24. 24.If a − b = 6 and ab = 16, what is a² + b²?
  25. 25.If a − b = 9 and ab = 10, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 96².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 24².
  28. 28.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 19².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 91².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 66².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 52².
  33. 33.Use a² − b² = (a + b)(a − b) to find 40² − 36².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 64².
  35. 35.Find the value of x² − y² when x = 12 and y = 8.
  36. 36.Use a² − b² = (a + b)(a − b) to find 60² − 4².
  37. 37.Use a² − b² = (a + b)(a − b) to find 76² − 46².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 86².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 45².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 63².

Answer key

  1. 9409
  2. 1596
  3. 1536
  4. 5041
  5. 72
  6. 4899
  7. 52
  8. 195
  9. 5
  10. 25
  11. 40
  12. 40
  13. 159
  14. 10
  15. 625
  16. 1296
  17. 336
  18. 2116
  19. 256
  20. 3584
  21. 148
  22. 3969
  23. 2065
  24. 68
  25. 101
  26. 9216
  27. 576
  28. 875
  29. 361
  30. 8281
  31. 4356
  32. 2704
  33. 304
  34. 4096
  35. 80
  36. 3584
  37. 3660
  38. 7396
  39. 2025
  40. 3969

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