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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 973 · 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 62 × 58.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 24².
  3. 3.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 104².
  5. 5.If a + b = 12 and ab = 20, what is a² + b²?
  6. 6.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  7. 7.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 31².
  9. 9.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  10. 10.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 75².
  12. 12.If a + b = 10 and ab = 21, what is a² + b²?
  13. 13.Use a² − b² = (a + b)(a − b) to find 59² − 48².
  14. 14.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  15. 15.Use (a + b)(a − b) = a² − b² to find 85 × 75.
  16. 16.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 99².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 84².
  19. 19.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  20. 20.Use (a − b)² = a² − 2ab + b² to find 62².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 102².
  22. 22.If a − b = 5 and ab = 6, what is a² + b²?
  23. 23.Use (a + b)(a − b) = a² − b² to find 108 × 92.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 21².
  25. 25.Find the value of x² − 2xy + y² when x = 7 and y = 5.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 83².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 51².
  28. 28.If a − b = 1 and ab = 6, what is a² + b²?
  29. 29.Use (a − b)² = a² − 2ab + b² to find 76².
  30. 30.Find the value of x² − 2xy + y² when x = 8 and y = 4.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 83².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 56².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 22².
  34. 34.If a − b = 4 and ab = 5, what is a² + b²?
  35. 35.Use a² − b² = (a + b)(a − b) to find 29² − 28².
  36. 36.If a + b = 8 and ab = 15, what is a² + b²?
  37. 37.Use (a − b)² = a² − 2ab + b² to find 12².
  38. 38.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  39. 39.If a + b = 3 and ab = 2, what is a² + b²?
  40. 40.Use (a − b)² = a² − 2ab + b² to find 78².

Answer key

  1. 3596
  2. 576
  3. 1564
  4. 10816
  5. 104
  6. 25
  7. 1591
  8. 961
  9. 4884
  10. 6351
  11. 5625
  12. 58
  13. 1177
  14. 4891
  15. 6375
  16. 3591
  17. 9801
  18. 7056
  19. 1551
  20. 3844
  21. 10404
  22. 37
  23. 9936
  24. 441
  25. 4
  26. 6889
  27. 2601
  28. 13
  29. 5776
  30. 16
  31. 6889
  32. 3136
  33. 484
  34. 26
  35. 57
  36. 34
  37. 144
  38. 9919
  39. 5
  40. 6084

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