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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 961 · 40 sums
TalentJR

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 21 × 19.
  2. 2.If a − b = 2 and ab = 3, what is a² + b²?
  3. 3.Use (a + b)² = a² + 2ab + b² to find 93².
  4. 4.If a + b = 3 and ab = 2, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 62².
  6. 6.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  7. 7.Use (a + b)² = a² + 2ab + b² to find 41².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 14².
  9. 9.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 74².
  11. 11.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 68².
  13. 13.Use a² − b² = (a + b)(a − b) to find 66² − 14².
  14. 14.Use a² − b² = (a + b)(a − b) to find 71² − 1².
  15. 15.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  16. 16.Find the value of x² − y² when x = 11 and y = 2.
  17. 17.Find the value of x² − 2xy + y² when x = 12 and y = 9.
  18. 18.Find the value of x² − y² when x = 12 and y = 6.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 48².
  20. 20.If a + b = 12 and ab = 11, what is a² + b²?
  21. 21.Find the value of x² + 2xy + y² when x = 12 and y = 7.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 102².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 95².
  24. 24.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  25. 25.Use a² − b² = (a + b)(a − b) to find 53² − 43².
  26. 26.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  27. 27.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 104².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 31².
  30. 30.Find the value of x² + 2xy + y² when x = 6 and y = 5.
  31. 31.Use a² − b² = (a + b)(a − b) to find 23² − 1².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 61².
  33. 33.Use a² − b² = (a + b)(a − b) to find 22² − 1².
  34. 34.Find the value of x² − 2xy + y² when x = 9 and y = 5.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 12².
  36. 36.Find the value of x² + 2xy + y² when x = 8 and y = 6.
  37. 37.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 88².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 107².
  40. 40.Use a² − b² = (a + b)(a − b) to find 82² − 28².

Answer key

  1. 399
  2. 10
  3. 8649
  4. 5
  5. 3844
  6. 884
  7. 1681
  8. 196
  9. 384
  10. 5476
  11. 391
  12. 4624
  13. 4160
  14. 5040
  15. 3551
  16. 117
  17. 9
  18. 108
  19. 2304
  20. 122
  21. 361
  22. 10404
  23. 9025
  24. 6384
  25. 960
  26. 875
  27. 49
  28. 10816
  29. 961
  30. 121
  31. 528
  32. 3721
  33. 483
  34. 16
  35. 144
  36. 196
  37. 9964
  38. 7744
  39. 11449
  40. 5940

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