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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 989 · 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 61².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 61².
  3. 3.If a + b = 7 and ab = 12, what is a² + b²?
  4. 4.Use (a + b)² = a² + 2ab + b² to find 77².
  5. 5.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 93².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 32².
  8. 8.If a + b = 18 and ab = 77, what is a² + b²?
  9. 9.If a + b = 15 and ab = 44, what is a² + b²?
  10. 10.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  11. 11.If a + b = 5 and ab = 6, what is a² + b²?
  12. 12.Find the value of x² + 2xy + y² when x = 15 and y = 9.
  13. 13.Use (a − b)² = a² − 2ab + b² to find 29².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 67².
  15. 15.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 27².
  17. 17.Find the value of x² − y² when x = 8 and y = 1.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 35².
  19. 19.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  20. 20.If a − b = 8 and ab = 20, what is a² + b²?
  21. 21.Use (a − b)² = a² − 2ab + b² to find 66².
  22. 22.Find the value of x² − 2xy + y² when x = 15 and y = 6.
  23. 23.Use a² − b² = (a + b)(a − b) to find 52² − 22².
  24. 24.Find the value of x² − y² when x = 3 and y = 1.
  25. 25.If a − b = 1 and ab = 2, what is a² + b²?
  26. 26.If a + b = 6 and ab = 5, what is a² + b²?
  27. 27.Find the value of x² + 2xy + y² when x = 14 and y = 1.
  28. 28.Find the value of x² + 2xy + y² when x = 8 and y = 5.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 11².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 72².
  31. 31.If a + b = 3 and ab = 2, what is a² + b²?
  32. 32.If a − b = 1 and ab = 12, what is a² + b²?
  33. 33.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  34. 34.Find the value of x² + 2xy + y² when x = 8 and y = 1.
  35. 35.Find the value of x² − y² when x = 10 and y = 6.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 16².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 13².
  38. 38.Use a² − b² = (a + b)(a − b) to find 77² − 65².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 71².
  40. 40.Use a² − b² = (a + b)(a − b) to find 61² − 52².

Answer key

  1. 3721
  2. 3721
  3. 25
  4. 5929
  5. 4819
  6. 8649
  7. 1024
  8. 170
  9. 137
  10. 3599
  11. 13
  12. 576
  13. 841
  14. 4489
  15. 3596
  16. 729
  17. 63
  18. 1225
  19. 8091
  20. 104
  21. 4356
  22. 81
  23. 2220
  24. 8
  25. 5
  26. 26
  27. 225
  28. 169
  29. 121
  30. 5184
  31. 5
  32. 25
  33. 25
  34. 81
  35. 64
  36. 256
  37. 169
  38. 1704
  39. 5041
  40. 1017

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