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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 908 · 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 72² − 17².
  2. 2.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  3. 3.If a + b = 14 and ab = 40, what is a² + b²?
  4. 4.Use a² − b² = (a + b)(a − b) to find 74² − 14².
  5. 5.Use a² − b² = (a + b)(a − b) to find 27² − 1².
  6. 6.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  7. 7.Find the value of x² + 2xy + y² when x = 15 and y = 2.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 74².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 16².
  10. 10.If a − b = 1 and ab = 30, what is a² + b²?
  11. 11.Find the value of x² − y² when x = 4 and y = 2.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 11².
  13. 13.Find the value of x² − y² when x = 5 and y = 2.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 44².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 52².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 48².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 21².
  18. 18.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 39².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 76².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 53².
  22. 22.If a + b = 4 and ab = 3, what is a² + b²?
  23. 23.If a + b = 5 and ab = 6, what is a² + b²?
  24. 24.Find the value of x² − y² when x = 9 and y = 7.
  25. 25.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  26. 26.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 37².
  28. 28.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  29. 29.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  30. 30.If a − b = 2 and ab = 8, what is a² + b²?
  31. 31.Use (a − b)² = a² − 2ab + b² to find 66².
  32. 32.Find the value of x² + 2xy + y² when x = 11 and y = 10.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 32².
  34. 34.Find the value of x² − 2xy + y² when x = 10 and y = 3.
  35. 35.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  36. 36.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  37. 37.If a + b = 14 and ab = 48, what is a² + b²?
  38. 38.Use (a + b)² = a² + 2ab + b² to find 75².
  39. 39.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  40. 40.Find the value of x² − y² when x = 3 and y = 2.

Answer key

  1. 4895
  2. 25
  3. 116
  4. 5280
  5. 728
  6. 836
  7. 289
  8. 5476
  9. 256
  10. 61
  11. 12
  12. 121
  13. 21
  14. 1936
  15. 2704
  16. 2304
  17. 441
  18. 49
  19. 1521
  20. 5776
  21. 2809
  22. 10
  23. 13
  24. 32
  25. 6396
  26. 384
  27. 1369
  28. 319
  29. 1
  30. 20
  31. 4356
  32. 441
  33. 1024
  34. 49
  35. 8036
  36. 3596
  37. 100
  38. 5625
  39. 851
  40. 5

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