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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 416 · 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 86².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 37².
  3. 3.Use a² − b² = (a + b)(a − b) to find 39² − 34².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 23².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 61².
  6. 6.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  7. 7.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  8. 8.Use a² − b² = (a + b)(a − b) to find 32² − 3².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 55².
  10. 10.Use a² − b² = (a + b)(a − b) to find 67² − 39².
  11. 11.Find the value of x² − y² when x = 7 and y = 4.
  12. 12.Use a² − b² = (a + b)(a − b) to find 88² − 49².
  13. 13.Use a² − b² = (a + b)(a − b) to find 23² − 21².
  14. 14.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  15. 15.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  16. 16.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  17. 17.Use a² − b² = (a + b)(a − b) to find 24² − 6².
  18. 18.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  19. 19.Use a² − b² = (a + b)(a − b) to find 21² − 16².
  20. 20.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 66².
  22. 22.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  23. 23.Use a² − b² = (a + b)(a − b) to find 95² − 94².
  24. 24.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 24².
  26. 26.Find the value of x² − 2xy + y² when x = 12 and y = 2.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 22².
  28. 28.If a − b = 3 and ab = 10, what is a² + b²?
  29. 29.Find the value of x² − 2xy + y² when x = 12 and y = 1.
  30. 30.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  31. 31.If a − b = 8 and ab = 33, what is a² + b²?
  32. 32.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  33. 33.Use a² − b² = (a + b)(a − b) to find 93² − 60².
  34. 34.Use a² − b² = (a + b)(a − b) to find 98² − 79².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 46².
  36. 36.Use a² − b² = (a + b)(a − b) to find 31² − 2².
  37. 37.If a + b = 3 and ab = 2, what is a² + b²?
  38. 38.Use a² − b² = (a + b)(a − b) to find 61² − 4².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 17².
  40. 40.If a + b = 6 and ab = 5, what is a² + b²?

Answer key

  1. 7396
  2. 1369
  3. 365
  4. 529
  5. 3721
  6. 9991
  7. 364
  8. 1015
  9. 3025
  10. 2968
  11. 33
  12. 5343
  13. 88
  14. 25
  15. 336
  16. 1599
  17. 540
  18. 391
  19. 185
  20. 819
  21. 4356
  22. 3575
  23. 189
  24. 49
  25. 576
  26. 100
  27. 484
  28. 29
  29. 121
  30. 6319
  31. 130
  32. 9975
  33. 5049
  34. 3363
  35. 2116
  36. 957
  37. 5
  38. 3705
  39. 289
  40. 26

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