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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 410 · 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)² = a² + 2ab + b² to find 66².
  2. 2.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 64².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 67².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 11².
  6. 6.If a + b = 10 and ab = 9, what is a² + b²?
  7. 7.Use (a + b)² = a² + 2ab + b² to find 73².
  8. 8.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  9. 9.Use a² − b² = (a + b)(a − b) to find 87² − 54².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 83².
  11. 11.Use a² − b² = (a + b)(a − b) to find 64² − 63².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 37².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 89².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 38².
  15. 15.If a + b = 11 and ab = 30, what is a² + b²?
  16. 16.If a + b = 15 and ab = 54, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 97².
  18. 18.If a + b = 11 and ab = 10, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 98².
  20. 20.Use a² − b² = (a + b)(a − b) to find 38² − 9².
  21. 21.Use a² − b² = (a + b)(a − b) to find 63² − 39².
  22. 22.Find the value of x² + 2xy + y² when x = 12 and y = 9.
  23. 23.Use (a − b)² = a² − 2ab + b² to find 34².
  24. 24.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 57².
  26. 26.Find the value of x² − 2xy + y² when x = 12 and y = 10.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 32².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 26².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 24².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 17².
  31. 31.Use a² − b² = (a + b)(a − b) to find 39² − 6².
  32. 32.Use a² − b² = (a + b)(a − b) to find 75² − 74².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 74².
  34. 34.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 55².
  36. 36.Find the value of x² − 2xy + y² when x = 15 and y = 1.
  37. 37.Use a² − b² = (a + b)(a − b) to find 80² − 1².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 49².
  39. 39.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  40. 40.Find the value of x² − 2xy + y² when x = 3 and y = 1.

Answer key

  1. 4356
  2. 351
  3. 4096
  4. 4489
  5. 121
  6. 82
  7. 5329
  8. 4896
  9. 4653
  10. 6889
  11. 127
  12. 1369
  13. 7921
  14. 1444
  15. 61
  16. 117
  17. 9409
  18. 101
  19. 9604
  20. 1363
  21. 2448
  22. 441
  23. 1156
  24. 1536
  25. 3249
  26. 4
  27. 1024
  28. 676
  29. 576
  30. 289
  31. 1485
  32. 149
  33. 5476
  34. 2436
  35. 3025
  36. 196
  37. 6399
  38. 2401
  39. 9975
  40. 4

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