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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 398 · 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 64² − 13².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 69².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 33².
  4. 4.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 13².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 83².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 37².
  8. 8.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  9. 9.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  10. 10.Use a² − b² = (a + b)(a − b) to find 90² − 65².
  11. 11.Find the value of x² − y² when x = 11 and y = 10.
  12. 12.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  13. 13.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 15².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 98².
  16. 16.If a + b = 18 and ab = 77, what is a² + b²?
  17. 17.Use (a + b)² = a² + 2ab + b² to find 88².
  18. 18.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  19. 19.If a + b = 10 and ab = 16, what is a² + b²?
  20. 20.Use a² − b² = (a + b)(a − b) to find 60² − 17².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 68².
  22. 22.Use a² − b² = (a + b)(a − b) to find 28² − 19².
  23. 23.Use a² − b² = (a + b)(a − b) to find 42² − 30².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 87².
  25. 25.If a − b = 2 and ab = 3, what is a² + b²?
  26. 26.Use a² − b² = (a + b)(a − b) to find 54² − 49².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 41².
  28. 28.If a − b = 8 and ab = 48, what is a² + b²?
  29. 29.Use (a + b)² = a² + 2ab + b² to find 106².
  30. 30.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 45².
  32. 32.Use a² − b² = (a + b)(a − b) to find 94² − 82².
  33. 33.If a − b = 4 and ab = 5, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 12².
  35. 35.Use a² − b² = (a + b)(a − b) to find 88² − 55².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 53².
  37. 37.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  38. 38.If a + b = 9 and ab = 14, what is a² + b²?
  39. 39.If a − b = 2 and ab = 35, what is a² + b²?
  40. 40.Use (a + b)² = a² + 2ab + b² to find 14².

Answer key

  1. 3927
  2. 4761
  3. 1089
  4. 8096
  5. 169
  6. 6889
  7. 1369
  8. 225
  9. 3551
  10. 3875
  11. 21
  12. 4884
  13. 3519
  14. 225
  15. 9604
  16. 170
  17. 7744
  18. 2436
  19. 68
  20. 3311
  21. 4624
  22. 423
  23. 864
  24. 7569
  25. 10
  26. 515
  27. 1681
  28. 160
  29. 11236
  30. 3599
  31. 2025
  32. 2112
  33. 26
  34. 144
  35. 4719
  36. 2809
  37. 319
  38. 53
  39. 74
  40. 196

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