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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 924 · 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 53² − 47².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 31².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 55².
  4. 4.Find the value of x² − y² when x = 3 and y = 1.
  5. 5.If a + b = 5 and ab = 6, what is a² + b²?
  6. 6.Use a² − b² = (a + b)(a − b) to find 83² − 11².
  7. 7.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  8. 8.Use a² − b² = (a + b)(a − b) to find 43² − 13².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 31².
  10. 10.Use a² − b² = (a + b)(a − b) to find 67² − 34².
  11. 11.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 24².
  13. 13.Use a² − b² = (a + b)(a − b) to find 42² − 11².
  14. 14.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 68².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 11².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 36².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 32².
  19. 19.Find the value of x² + 2xy + y² when x = 6 and y = 2.
  20. 20.Use (a − b)² = a² − 2ab + b² to find 21².
  21. 21.If a + b = 4 and ab = 3, what is a² + b²?
  22. 22.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  23. 23.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  24. 24.Find the value of x² + 2xy + y² when x = 13 and y = 9.
  25. 25.If a + b = 22 and ab = 120, what is a² + b²?
  26. 26.Use a² − b² = (a + b)(a − b) to find 27² − 2².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 74².
  28. 28.Use a² − b² = (a + b)(a − b) to find 66² − 16².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 37².
  30. 30.Find the value of x² − 2xy + y² when x = 10 and y = 1.
  31. 31.Find the value of x² − 2xy + y² when x = 9 and y = 7.
  32. 32.If a + b = 16 and ab = 63, what is a² + b²?
  33. 33.Use (a − b)² = a² − 2ab + b² to find 79².
  34. 34.Find the value of x² − 2xy + y² when x = 7 and y = 6.
  35. 35.Use (a + b)(a − b) = a² − b² to find 108 × 92.
  36. 36.Use a² − b² = (a + b)(a − b) to find 83² − 9².
  37. 37.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 68².
  39. 39.Find the value of x² − 2xy + y² when x = 8 and y = 1.
  40. 40.Find the value of x² + 2xy + y² when x = 7 and y = 3.

Answer key

  1. 600
  2. 961
  3. 3025
  4. 8
  5. 13
  6. 6768
  7. 396
  8. 1680
  9. 961
  10. 3333
  11. 875
  12. 576
  13. 1643
  14. 9
  15. 4624
  16. 121
  17. 1296
  18. 1024
  19. 64
  20. 441
  21. 10
  22. 391
  23. 3596
  24. 484
  25. 244
  26. 725
  27. 5476
  28. 4100
  29. 1369
  30. 81
  31. 4
  32. 130
  33. 6241
  34. 1
  35. 9936
  36. 6808
  37. 2484
  38. 4624
  39. 49
  40. 100

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