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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 557 · 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 (a + b)(a − b) = a² − b² to find 52 × 48.
  2. 2.If a − b = 5 and ab = 84, what is a² + b²?
  3. 3.Use a² − b² = (a + b)(a − b) to find 66² − 44².
  4. 4.Use a² − b² = (a + b)(a − b) to find 89² − 30².
  5. 5.Find the value of x² + 2xy + y² when x = 13 and y = 9.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 49².
  7. 7.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  8. 8.Use a² − b² = (a + b)(a − b) to find 62² − 25².
  9. 9.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 45².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 26².
  12. 12.If a + b = 11 and ab = 30, what is a² + b²?
  13. 13.Find the value of x² − 2xy + y² when x = 10 and y = 2.
  14. 14.If a − b = 3 and ab = 108, what is a² + b²?
  15. 15.Use a² − b² = (a + b)(a − b) to find 67² − 16².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 74².
  17. 17.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  18. 18.Find the value of x² − y² when x = 3 and y = 2.
  19. 19.Use a² − b² = (a + b)(a − b) to find 50² − 15².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 37².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 97².
  22. 22.Find the value of x² − y² when x = 12 and y = 9.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 46².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 24².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 93².
  26. 26.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  27. 27.Find the value of x² − y² when x = 8 and y = 1.
  28. 28.Use a² − b² = (a + b)(a − b) to find 24² − 12².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 65².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 68².
  31. 31.Use a² − b² = (a + b)(a − b) to find 48² − 35².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 21².
  33. 33.If a + b = 7 and ab = 12, what is a² + b²?
  34. 34.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  35. 35.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  36. 36.If a + b = 10 and ab = 24, what is a² + b²?
  37. 37.If a + b = 13 and ab = 36, what is a² + b²?
  38. 38.Use (a + b)² = a² + 2ab + b² to find 59².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 11².
  40. 40.If a + b = 5 and ab = 4, what is a² + b²?

Answer key

  1. 2496
  2. 193
  3. 2420
  4. 7021
  5. 484
  6. 2401
  7. 896
  8. 3219
  9. 2451
  10. 2025
  11. 676
  12. 61
  13. 64
  14. 225
  15. 4233
  16. 5476
  17. 6364
  18. 5
  19. 2275
  20. 1369
  21. 9409
  22. 63
  23. 2116
  24. 576
  25. 8649
  26. 1536
  27. 63
  28. 432
  29. 4225
  30. 4624
  31. 1079
  32. 441
  33. 25
  34. 851
  35. 2436
  36. 52
  37. 97
  38. 3481
  39. 121
  40. 17

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