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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 75 · 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 36² − 22².
  2. 2.Find the value of x² − 2xy + y² when x = 7 and y = 4.
  3. 3.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  4. 4.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 88².
  6. 6.Use a² − b² = (a + b)(a − b) to find 20² − 4².
  7. 7.Use a² − b² = (a + b)(a − b) to find 52² − 24².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 79².
  9. 9.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 78².
  11. 11.Find the value of x² + 2xy + y² when x = 9 and y = 5.
  12. 12.Use a² − b² = (a + b)(a − b) to find 84² − 19².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 46².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 29².
  15. 15.Find the value of x² − 2xy + y² when x = 9 and y = 4.
  16. 16.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  17. 17.Find the value of x² − y² when x = 7 and y = 5.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 101².
  19. 19.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  20. 20.Use (a + b)² = a² + 2ab + b² to find 73².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 94².
  22. 22.Find the value of x² − y² when x = 6 and y = 2.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 27².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 106².
  25. 25.If a − b = 3 and ab = 4, what is a² + b²?
  26. 26.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  27. 27.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  28. 28.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  29. 29.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  30. 30.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 99².
  32. 32.If a − b = 1 and ab = 6, what is a² + b²?
  33. 33.Find the value of x² + 2xy + y² when x = 6 and y = 2.
  34. 34.If a − b = 8 and ab = 33, what is a² + b²?
  35. 35.Find the value of x² − y² when x = 3 and y = 2.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 48².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 81².
  38. 38.Find the value of x² + 2xy + y² when x = 13 and y = 8.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 85².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 11².

Answer key

  1. 812
  2. 9
  3. 2496
  4. 25
  5. 7744
  6. 384
  7. 2128
  8. 6241
  9. 225
  10. 6084
  11. 196
  12. 6695
  13. 2116
  14. 841
  15. 25
  16. 8019
  17. 24
  18. 10201
  19. 9999
  20. 5329
  21. 8836
  22. 32
  23. 729
  24. 11236
  25. 17
  26. 2419
  27. 9964
  28. 1591
  29. 49
  30. 36
  31. 9801
  32. 13
  33. 64
  34. 130
  35. 5
  36. 2304
  37. 6561
  38. 441
  39. 7225
  40. 121

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