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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 203 · 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)(a − b) = a² − b² to find 84 × 76.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 19².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 97².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 23².
  5. 5.Use a² − b² = (a + b)(a − b) to find 84² − 45².
  6. 6.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  7. 7.If a − b = 3 and ab = 108, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 25².
  9. 9.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  10. 10.Use a² − b² = (a + b)(a − b) to find 86² − 2².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 35².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 14².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 94².
  14. 14.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  15. 15.If a + b = 3 and ab = 2, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 41².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 49².
  18. 18.Find the value of x² − y² when x = 4 and y = 1.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 67².
  20. 20.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  21. 21.Use a² − b² = (a + b)(a − b) to find 62² − 24².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 95².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 15².
  24. 24.If a + b = 10 and ab = 16, what is a² + b²?
  25. 25.Use (a − b)² = a² − 2ab + b² to find 49².
  26. 26.Find the value of x² − 2xy + y² when x = 6 and y = 4.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 46².
  28. 28.If a − b = 10 and ab = 11, what is a² + b²?
  29. 29.If a − b = 2 and ab = 120, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 26² − 14².
  31. 31.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  32. 32.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  33. 33.If a + b = 11 and ab = 30, what is a² + b²?
  34. 34.Use a² − b² = (a + b)(a − b) to find 81² − 68².
  35. 35.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  36. 36.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  37. 37.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 36².
  39. 39.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 72².

Answer key

  1. 6384
  2. 361
  3. 9409
  4. 529
  5. 5031
  6. 3591
  7. 225
  8. 625
  9. 6336
  10. 7392
  11. 1225
  12. 196
  13. 8836
  14. 1564
  15. 5
  16. 1681
  17. 2401
  18. 15
  19. 4489
  20. 896
  21. 3268
  22. 9025
  23. 225
  24. 68
  25. 2401
  26. 4
  27. 2116
  28. 122
  29. 244
  30. 480
  31. 875
  32. 9964
  33. 61
  34. 1937
  35. 836
  36. 6399
  37. 1551
  38. 1296
  39. 351
  40. 5184

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