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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 290 · 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)(a − b) = a² − b² to find 44 × 36.
  2. 2.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  3. 3.Use a² − b² = (a + b)(a − b) to find 37² − 7².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 96².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 28².
  6. 6.If a − b = 1 and ab = 2, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 98².
  8. 8.Use a² − b² = (a + b)(a − b) to find 81² − 31².
  9. 9.Find the value of x² − 2xy + y² when x = 14 and y = 1.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 63².
  11. 11.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  12. 12.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  13. 13.If a − b = 1 and ab = 20, what is a² + b²?
  14. 14.If a + b = 6 and ab = 5, what is a² + b²?
  15. 15.Use (a − b)² = a² − 2ab + b² to find 59².
  16. 16.If a − b = 5 and ab = 14, what is a² + b²?
  17. 17.If a − b = 4 and ab = 96, what is a² + b²?
  18. 18.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  19. 19.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  20. 20.Find the value of x² − 2xy + y² when x = 8 and y = 6.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 52².
  22. 22.Find the value of x² + 2xy + y² when x = 12 and y = 9.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 58².
  24. 24.Find the value of x² − 2xy + y² when x = 9 and y = 3.
  25. 25.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  26. 26.Find the value of x² + 2xy + y² when x = 11 and y = 8.
  27. 27.Find the value of x² − y² when x = 14 and y = 7.
  28. 28.If a + b = 15 and ab = 56, what is a² + b²?
  29. 29.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  30. 30.If a − b = 6 and ab = 27, what is a² + b²?
  31. 31.Use (a + b)² = a² + 2ab + b² to find 37².
  32. 32.Find the value of x² − y² when x = 7 and y = 4.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 18².
  34. 34.Find the value of x² − 2xy + y² when x = 7 and y = 4.
  35. 35.Find the value of x² − y² when x = 9 and y = 7.
  36. 36.Use a² − b² = (a + b)(a − b) to find 64² − 17².
  37. 37.Use a² − b² = (a + b)(a − b) to find 80² − 18².
  38. 38.Use a² − b² = (a + b)(a − b) to find 28² − 15².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 88².
  40. 40.If a − b = 2 and ab = 120, what is a² + b²?

Answer key

  1. 1584
  2. 4891
  3. 1320
  4. 9216
  5. 784
  6. 5
  7. 9604
  8. 5600
  9. 169
  10. 3969
  11. 384
  12. 2419
  13. 41
  14. 26
  15. 3481
  16. 53
  17. 208
  18. 4896
  19. 1
  20. 4
  21. 2704
  22. 441
  23. 3364
  24. 36
  25. 864
  26. 361
  27. 147
  28. 113
  29. 9951
  30. 90
  31. 1369
  32. 33
  33. 324
  34. 9
  35. 32
  36. 3807
  37. 6076
  38. 559
  39. 7744
  40. 244

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