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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 366 · 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 = 9 and y = 7.
  2. 2.If a − b = 5 and ab = 36, what is a² + b²?
  3. 3.Use a² − b² = (a + b)(a − b) to find 96² − 77².
  4. 4.Find the value of x² + 2xy + y² when x = 10 and y = 2.
  5. 5.Find the value of x² + 2xy + y² when x = 13 and y = 5.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 11².
  7. 7.Use a² − b² = (a + b)(a − b) to find 39² − 21².
  8. 8.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  9. 9.Find the value of x² + 2xy + y² when x = 15 and y = 1.
  10. 10.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  11. 11.If a + b = 14 and ab = 33, what is a² + b²?
  12. 12.Use a² − b² = (a + b)(a − b) to find 82² − 4².
  13. 13.Use a² − b² = (a + b)(a − b) to find 76² − 20².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 107².
  15. 15.Use a² − b² = (a + b)(a − b) to find 42² − 21².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 34².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 53².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 93².
  19. 19.If a + b = 12 and ab = 32, what is a² + b²?
  20. 20.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  21. 21.Use a² − b² = (a + b)(a − b) to find 70² − 56².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 69².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 95².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 99².
  25. 25.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  26. 26.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  27. 27.If a + b = 10 and ab = 21, what is a² + b²?
  28. 28.If a − b = 1 and ab = 2, what is a² + b²?
  29. 29.Use (a − b)² = a² − 2ab + b² to find 75².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 69².
  31. 31.If a + b = 16 and ab = 60, what is a² + b²?
  32. 32.Find the value of x² − y² when x = 11 and y = 5.
  33. 33.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  34. 34.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 11².
  36. 36.Use a² − b² = (a + b)(a − b) to find 30² − 24².
  37. 37.If a + b = 12 and ab = 11, what is a² + b²?
  38. 38.If a + b = 15 and ab = 56, what is a² + b²?
  39. 39.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  40. 40.Use a² − b² = (a + b)(a − b) to find 85² − 35².

Answer key

  1. 4
  2. 97
  3. 3287
  4. 144
  5. 324
  6. 121
  7. 1080
  8. 6396
  9. 256
  10. 1
  11. 130
  12. 6708
  13. 5376
  14. 11449
  15. 1323
  16. 1156
  17. 2809
  18. 8649
  19. 80
  20. 6384
  21. 1764
  22. 4761
  23. 9025
  24. 9801
  25. 8084
  26. 3519
  27. 58
  28. 5
  29. 5625
  30. 4761
  31. 136
  32. 96
  33. 819
  34. 9
  35. 121
  36. 324
  37. 122
  38. 113
  39. 6351
  40. 6000

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