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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 488 · 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 43 × 37.
  2. 2.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  3. 3.If a − b = 7 and ab = 18, what is a² + b²?
  4. 4.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  5. 5.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 26².
  7. 7.Use a² − b² = (a + b)(a − b) to find 36² − 8².
  8. 8.If a + b = 19 and ab = 88, what is a² + b²?
  9. 9.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 98².
  11. 11.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  12. 12.Find the value of x² − y² when x = 7 and y = 6.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 96².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 27².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 16².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 14².
  17. 17.Find the value of x² − 2xy + y² when x = 7 and y = 4.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 15².
  19. 19.If a − b = 6 and ab = 16, what is a² + b²?
  20. 20.Use a² − b² = (a + b)(a − b) to find 24² − 23².
  21. 21.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 59².
  23. 23.Find the value of x² − 2xy + y² when x = 9 and y = 6.
  24. 24.Find the value of x² + 2xy + y² when x = 13 and y = 12.
  25. 25.Find the value of x² + 2xy + y² when x = 14 and y = 12.
  26. 26.Use a² − b² = (a + b)(a − b) to find 57² − 49².
  27. 27.Find the value of x² − 2xy + y² when x = 15 and y = 1.
  28. 28.If a − b = 2 and ab = 8, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 24² − 12².
  30. 30.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 98².
  32. 32.If a − b = 9 and ab = 36, what is a² + b²?
  33. 33.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  34. 34.If a + b = 3 and ab = 2, what is a² + b²?
  35. 35.If a + b = 20 and ab = 96, what is a² + b²?
  36. 36.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 93².
  38. 38.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  39. 39.Find the value of x² + 2xy + y² when x = 9 and y = 6.
  40. 40.Use a² − b² = (a + b)(a − b) to find 73² − 61².

Answer key

  1. 1591
  2. 3575
  3. 85
  4. 8091
  5. 4819
  6. 676
  7. 1232
  8. 185
  9. 25
  10. 9604
  11. 875
  12. 13
  13. 9216
  14. 729
  15. 256
  16. 196
  17. 9
  18. 225
  19. 68
  20. 47
  21. 364
  22. 3481
  23. 9
  24. 625
  25. 676
  26. 848
  27. 196
  28. 20
  29. 432
  30. 81
  31. 9604
  32. 153
  33. 896
  34. 5
  35. 208
  36. 1599
  37. 8649
  38. 36
  39. 225
  40. 1608

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