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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 869 · 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 53² − 39².
  2. 2.Find the value of x² + 2xy + y² when x = 7 and y = 3.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 34².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 54².
  5. 5.Find the value of x² + 2xy + y² when x = 6 and y = 4.
  6. 6.Find the value of x² − y² when x = 3 and y = 2.
  7. 7.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  8. 8.Use a² − b² = (a + b)(a − b) to find 69² − 51².
  9. 9.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 99².
  11. 11.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  12. 12.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 36².
  14. 14.If a + b = 5 and ab = 6, what is a² + b²?
  15. 15.Use (a − b)² = a² − 2ab + b² to find 64².
  16. 16.Find the value of x² − 2xy + y² when x = 10 and y = 3.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 31².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 96².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 25².
  20. 20.Use a² − b² = (a + b)(a − b) to find 59² − 47².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 52².
  22. 22.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  23. 23.Find the value of x² + 2xy + y² when x = 9 and y = 5.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 97².
  25. 25.If a − b = 5 and ab = 24, what is a² + b²?
  26. 26.Use (a − b)² = a² − 2ab + b² to find 73².
  27. 27.If a + b = 4 and ab = 3, what is a² + b²?
  28. 28.Use a² − b² = (a + b)(a − b) to find 44² − 1².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 75².
  30. 30.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  31. 31.Find the value of x² − 2xy + y² when x = 13 and y = 4.
  32. 32.Use (a + b)² = a² + 2ab + b² to find 22².
  33. 33.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  34. 34.Find the value of x² + 2xy + y² when x = 14 and y = 5.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 28².
  36. 36.Find the value of x² − y² when x = 10 and y = 2.
  37. 37.Use a² − b² = (a + b)(a − b) to find 82² − 79².
  38. 38.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 55².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 35².

Answer key

  1. 1288
  2. 100
  3. 1156
  4. 2916
  5. 100
  6. 5
  7. 899
  8. 2160
  9. 1591
  10. 9801
  11. 6396
  12. 2496
  13. 1296
  14. 13
  15. 4096
  16. 49
  17. 961
  18. 9216
  19. 625
  20. 1272
  21. 2704
  22. 25
  23. 196
  24. 9409
  25. 73
  26. 5329
  27. 10
  28. 1935
  29. 5625
  30. 9991
  31. 81
  32. 484
  33. 6364
  34. 361
  35. 784
  36. 96
  37. 483
  38. 819
  39. 3025
  40. 1225

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