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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 538 · 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 93² − 27².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 102².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 31².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 69².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 16².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 33².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 41².
  8. 8.Use a² − b² = (a + b)(a − b) to find 20² − 4².
  9. 9.Find the value of x² − y² when x = 7 and y = 1.
  10. 10.Use a² − b² = (a + b)(a − b) to find 27² − 16².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 27².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 91².
  13. 13.Use a² − b² = (a + b)(a − b) to find 91² − 67².
  14. 14.If a + b = 12 and ab = 35, what is a² + b²?
  15. 15.Use a² − b² = (a + b)(a − b) to find 95² − 56².
  16. 16.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  17. 17.Use a² − b² = (a + b)(a − b) to find 87² − 59².
  18. 18.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 83².
  20. 20.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 44².
  22. 22.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  23. 23.If a − b = 2 and ab = 8, what is a² + b²?
  24. 24.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  25. 25.If a − b = 1 and ab = 12, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 39².
  27. 27.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 55².
  29. 29.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  30. 30.If a + b = 18 and ab = 77, what is a² + b²?
  31. 31.If a + b = 5 and ab = 4, what is a² + b²?
  32. 32.Use (a − b)² = a² − 2ab + b² to find 36².
  33. 33.Find the value of x² − y² when x = 10 and y = 2.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 89².
  35. 35.Find the value of x² − 2xy + y² when x = 11 and y = 9.
  36. 36.Use a² − b² = (a + b)(a − b) to find 70² − 27².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 11².
  38. 38.If a + b = 6 and ab = 8, what is a² + b²?
  39. 39.If a + b = 7 and ab = 12, what is a² + b²?
  40. 40.Use (a − b)² = a² − 2ab + b² to find 22².

Answer key

  1. 7920
  2. 10404
  3. 961
  4. 4761
  5. 256
  6. 1089
  7. 1681
  8. 384
  9. 48
  10. 473
  11. 729
  12. 8281
  13. 3792
  14. 74
  15. 5889
  16. 3596
  17. 4088
  18. 6336
  19. 6889
  20. 144
  21. 1936
  22. 819
  23. 20
  24. 4891
  25. 25
  26. 1521
  27. 1596
  28. 3025
  29. 3584
  30. 170
  31. 17
  32. 1296
  33. 96
  34. 7921
  35. 4
  36. 4171
  37. 121
  38. 20
  39. 25
  40. 484

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