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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 551 · 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 46².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 59².
  3. 3.Use a² − b² = (a + b)(a − b) to find 93² − 29².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 69².
  5. 5.If a + b = 13 and ab = 12, what is a² + b²?
  6. 6.Use (a − b)² = a² − 2ab + b² to find 34².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 61².
  8. 8.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  9. 9.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  10. 10.Find the value of x² + 2xy + y² when x = 14 and y = 7.
  11. 11.Use a² − b² = (a + b)(a − b) to find 85² − 33².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 92².
  13. 13.If a − b = 3 and ab = 10, what is a² + b²?
  14. 14.Use (a + b)² = a² + 2ab + b² to find 39².
  15. 15.Find the value of x² + 2xy + y² when x = 10 and y = 1.
  16. 16.Find the value of x² − y² when x = 13 and y = 3.
  17. 17.Find the value of x² − 2xy + y² when x = 4 and y = 3.
  18. 18.If a + b = 9 and ab = 18, what is a² + b²?
  19. 19.Use a² − b² = (a + b)(a − b) to find 49² − 45².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 85².
  21. 21.If a − b = 1 and ab = 42, what is a² + b²?
  22. 22.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  23. 23.Find the value of x² + 2xy + y² when x = 15 and y = 3.
  24. 24.Use a² − b² = (a + b)(a − b) to find 76² − 75².
  25. 25.If a − b = 6 and ab = 27, what is a² + b²?
  26. 26.Use a² − b² = (a + b)(a − b) to find 81² − 12².
  27. 27.Find the value of x² − y² when x = 9 and y = 8.
  28. 28.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  29. 29.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  30. 30.Use a² − b² = (a + b)(a − b) to find 70² − 14².
  31. 31.If a + b = 15 and ab = 36, what is a² + b²?
  32. 32.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 39².
  34. 34.Use a² − b² = (a + b)(a − b) to find 38² − 10².
  35. 35.Find the value of x² − y² when x = 8 and y = 3.
  36. 36.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  37. 37.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  38. 38.Use a² − b² = (a + b)(a − b) to find 84² − 60².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 83².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 67².

Answer key

  1. 2116
  2. 3481
  3. 7808
  4. 4761
  5. 145
  6. 1156
  7. 3721
  8. 3519
  9. 391
  10. 441
  11. 6136
  12. 8464
  13. 29
  14. 1521
  15. 121
  16. 160
  17. 1
  18. 45
  19. 376
  20. 7225
  21. 85
  22. 3536
  23. 324
  24. 151
  25. 90
  26. 6417
  27. 17
  28. 896
  29. 351
  30. 4704
  31. 153
  32. 36
  33. 1521
  34. 1344
  35. 55
  36. 2451
  37. 9951
  38. 3456
  39. 6889
  40. 4489

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