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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 537 · 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 34² − 1².
  2. 2.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  3. 3.Use a² − b² = (a + b)(a − b) to find 32² − 1².
  4. 4.If a − b = 2 and ab = 3, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 31².
  6. 6.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  7. 7.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  8. 8.Find the value of x² − 2xy + y² when x = 12 and y = 3.
  9. 9.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  10. 10.Find the value of x² − y² when x = 7 and y = 6.
  11. 11.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  12. 12.Find the value of x² − 2xy + y² when x = 7 and y = 5.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 39².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 54².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 48².
  16. 16.If a + b = 17 and ab = 72, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 18².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 33².
  19. 19.Use a² − b² = (a + b)(a − b) to find 32² − 10².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 77².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 35².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 18².
  23. 23.Find the value of x² + 2xy + y² when x = 15 and y = 14.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 95².
  25. 25.Find the value of x² − 2xy + y² when x = 12 and y = 4.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 107².
  27. 27.Use a² − b² = (a + b)(a − b) to find 90² − 42².
  28. 28.Find the value of x² + 2xy + y² when x = 13 and y = 10.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 19².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 86².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 15².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 41².
  33. 33.Find the value of x² − y² when x = 11 and y = 10.
  34. 34.Use a² − b² = (a + b)(a − b) to find 80² − 45².
  35. 35.Use a² − b² = (a + b)(a − b) to find 75² − 68².
  36. 36.Find the value of x² + 2xy + y² when x = 10 and y = 3.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 37².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 52².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 24².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 98².

Answer key

  1. 1155
  2. 1564
  3. 1023
  4. 10
  5. 961
  6. 1536
  7. 3599
  8. 81
  9. 8091
  10. 13
  11. 391
  12. 4
  13. 1521
  14. 2916
  15. 2304
  16. 145
  17. 324
  18. 1089
  19. 924
  20. 5929
  21. 1225
  22. 324
  23. 841
  24. 9025
  25. 64
  26. 11449
  27. 6336
  28. 529
  29. 361
  30. 7396
  31. 225
  32. 1681
  33. 21
  34. 4375
  35. 1001
  36. 169
  37. 1369
  38. 2704
  39. 576
  40. 9604

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