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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 948 · 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.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  2. 2.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  3. 3.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 62².
  5. 5.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  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 59 × 41.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 33².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 54².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 87².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 94².
  12. 12.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  13. 13.Use (a − b)² = a² − 2ab + b² to find 69².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 68².
  15. 15.Use a² − b² = (a + b)(a − b) to find 85² − 7².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 98².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 77².
  18. 18.Find the value of x² + 2xy + y² when x = 8 and y = 4.
  19. 19.If a + b = 7 and ab = 12, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 96².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 37².
  22. 22.Find the value of x² − y² when x = 15 and y = 4.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 39².
  24. 24.Find the value of x² + 2xy + y² when x = 15 and y = 13.
  25. 25.If a + b = 17 and ab = 66, what is a² + b²?
  26. 26.If a + b = 15 and ab = 56, what is a² + b²?
  27. 27.Find the value of x² + 2xy + y² when x = 14 and y = 4.
  28. 28.Find the value of x² − y² when x = 12 and y = 10.
  29. 29.Find the value of x² + 2xy + y² when x = 14 and y = 2.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 51².
  31. 31.Use a² − b² = (a + b)(a − b) to find 39² − 18².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 42².
  33. 33.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  34. 34.If a − b = 2 and ab = 15, what is a² + b²?
  35. 35.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 103².
  37. 37.Find the value of x² − 2xy + y² when x = 13 and y = 6.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 64².
  39. 39.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  40. 40.If a + b = 3 and ab = 2, what is a² + b²?

Answer key

  1. 25
  2. 36
  3. 6319
  4. 3844
  5. 3599
  6. 5
  7. 2419
  8. 1089
  9. 2916
  10. 7569
  11. 8836
  12. 144
  13. 4761
  14. 4624
  15. 7176
  16. 9604
  17. 5929
  18. 144
  19. 25
  20. 9216
  21. 1369
  22. 209
  23. 1521
  24. 784
  25. 157
  26. 113
  27. 324
  28. 44
  29. 256
  30. 2601
  31. 1197
  32. 1764
  33. 49
  34. 34
  35. 3551
  36. 10609
  37. 49
  38. 4096
  39. 836
  40. 5

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