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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 624 · 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 = 11 and y = 9.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 39².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 67².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 106².
  5. 5.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 72².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 59².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 93².
  9. 9.Find the value of x² − 2xy + y² when x = 12 and y = 2.
  10. 10.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 87².
  12. 12.Use a² − b² = (a + b)(a − b) to find 43² − 41².
  13. 13.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 42².
  15. 15.Use a² − b² = (a + b)(a − b) to find 82² − 59².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 82².
  17. 17.Find the value of x² − 2xy + y² when x = 12 and y = 7.
  18. 18.If a − b = 1 and ab = 110, what is a² + b²?
  19. 19.Use (a + b)² = a² + 2ab + b² to find 24².
  20. 20.If a − b = 3 and ab = 18, what is a² + b²?
  21. 21.Use (a + b)² = a² + 2ab + b² to find 21².
  22. 22.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  23. 23.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  24. 24.If a − b = 4 and ab = 60, what is a² + b²?
  25. 25.Use (a + b)² = a² + 2ab + b² to find 85².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 29².
  27. 27.If a + b = 5 and ab = 6, what is a² + b²?
  28. 28.Use a² − b² = (a + b)(a − b) to find 52² − 2².
  29. 29.Use a² − b² = (a + b)(a − b) to find 88² − 40².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 86².
  31. 31.Use a² − b² = (a + b)(a − b) to find 63² − 40².
  32. 32.If a + b = 3 and ab = 2, what is a² + b²?
  33. 33.Use (a + b)² = a² + 2ab + b² to find 19².
  34. 34.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  35. 35.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  36. 36.If a + b = 10 and ab = 21, what is a² + b²?
  37. 37.Use (a − b)² = a² − 2ab + b² to find 81².
  38. 38.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  39. 39.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 23².

Answer key

  1. 400
  2. 1521
  3. 4489
  4. 11236
  5. 49
  6. 5184
  7. 3481
  8. 8649
  9. 100
  10. 896
  11. 7569
  12. 168
  13. 3596
  14. 1764
  15. 3243
  16. 6724
  17. 25
  18. 221
  19. 576
  20. 45
  21. 441
  22. 3575
  23. 399
  24. 136
  25. 7225
  26. 841
  27. 13
  28. 2700
  29. 6144
  30. 7396
  31. 2369
  32. 5
  33. 361
  34. 6319
  35. 1551
  36. 58
  37. 6561
  38. 6336
  39. 2484
  40. 529

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