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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 568 · 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 a² − b² = (a + b)(a − b) to find 92² − 75².
  2. 2.Find the value of x² + 2xy + y² when x = 10 and y = 6.
  3. 3.If a + b = 3 and ab = 2, what is a² + b²?
  4. 4.Use (a + b)² = a² + 2ab + b² to find 67².
  5. 5.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  6. 6.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  7. 7.Use a² − b² = (a + b)(a − b) to find 39² − 32².
  8. 8.If a − b = 1 and ab = 72, what is a² + b²?
  9. 9.Use (a − b)² = a² − 2ab + b² to find 55².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 11².
  11. 11.Find the value of x² − y² when x = 5 and y = 3.
  12. 12.Use a² − b² = (a + b)(a − b) to find 42² − 32².
  13. 13.If a + b = 7 and ab = 12, what is a² + b²?
  14. 14.Use (a + b)² = a² + 2ab + b² to find 91².
  15. 15.If a + b = 13 and ab = 42, what is a² + b²?
  16. 16.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 78².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 65².
  19. 19.If a + b = 9 and ab = 8, what is a² + b²?
  20. 20.Use a² − b² = (a + b)(a − b) to find 50² − 15².
  21. 21.Find the value of x² + 2xy + y² when x = 13 and y = 3.
  22. 22.Find the value of x² − y² when x = 8 and y = 1.
  23. 23.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  24. 24.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  25. 25.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 42².
  27. 27.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  28. 28.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  29. 29.Use a² − b² = (a + b)(a − b) to find 86² − 82².
  30. 30.If a − b = 1 and ab = 132, what is a² + b²?
  31. 31.Use (a + b)² = a² + 2ab + b² to find 81².
  32. 32.If a − b = 4 and ab = 60, what is a² + b²?
  33. 33.Use (a − b)² = a² − 2ab + b² to find 35².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 58².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 52².
  36. 36.If a + b = 5 and ab = 6, what is a² + b²?
  37. 37.If a + b = 17 and ab = 72, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 19².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 12².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 16².

Answer key

  1. 2839
  2. 256
  3. 5
  4. 4489
  5. 4899
  6. 9964
  7. 497
  8. 145
  9. 3025
  10. 121
  11. 16
  12. 740
  13. 25
  14. 8281
  15. 85
  16. 8075
  17. 6084
  18. 4225
  19. 65
  20. 2275
  21. 256
  22. 63
  23. 851
  24. 2464
  25. 2499
  26. 1764
  27. 1
  28. 3575
  29. 672
  30. 265
  31. 6561
  32. 136
  33. 1225
  34. 3364
  35. 2704
  36. 13
  37. 145
  38. 361
  39. 144
  40. 256

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