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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 471 · 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 99².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 57².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 67².
  4. 4.If a + b = 7 and ab = 12, what is a² + b²?
  5. 5.If a − b = 2 and ab = 15, what is a² + b²?
  6. 6.Use a² − b² = (a + b)(a − b) to find 38² − 9².
  7. 7.Find the value of x² − 2xy + y² when x = 14 and y = 9.
  8. 8.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  9. 9.Find the value of x² − 2xy + y² when x = 8 and y = 3.
  10. 10.Find the value of x² − y² when x = 3 and y = 2.
  11. 11.If a + b = 16 and ab = 63, what is a² + b²?
  12. 12.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  13. 13.Use a² − b² = (a + b)(a − b) to find 97² − 11².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 94².
  15. 15.Use a² − b² = (a + b)(a − b) to find 68² − 2².
  16. 16.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  17. 17.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  18. 18.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  19. 19.Find the value of x² − y² when x = 14 and y = 1.
  20. 20.If a + b = 19 and ab = 88, what is a² + b²?
  21. 21.Find the value of x² + 2xy + y² when x = 9 and y = 4.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 83².
  23. 23.If a − b = 5 and ab = 36, what is a² + b²?
  24. 24.Use (a − b)² = a² − 2ab + b² to find 19².
  25. 25.If a − b = 5 and ab = 24, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 76².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 43².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 14².
  29. 29.Find the value of x² + 2xy + y² when x = 6 and y = 4.
  30. 30.Use a² − b² = (a + b)(a − b) to find 85² − 6².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 69².
  32. 32.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  33. 33.Use a² − b² = (a + b)(a − b) to find 24² − 6².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 64².
  35. 35.If a + b = 8 and ab = 15, what is a² + b²?
  36. 36.Use (a + b)² = a² + 2ab + b² to find 15².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 17².
  38. 38.Use a² − b² = (a + b)(a − b) to find 95² − 21².
  39. 39.If a − b = 1 and ab = 2, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 88² − 70².

Answer key

  1. 9801
  2. 3249
  3. 4489
  4. 25
  5. 34
  6. 1363
  7. 25
  8. 364
  9. 25
  10. 5
  11. 130
  12. 6384
  13. 9288
  14. 8836
  15. 4620
  16. 4851
  17. 1575
  18. 3536
  19. 195
  20. 185
  21. 169
  22. 6889
  23. 97
  24. 361
  25. 73
  26. 5776
  27. 1849
  28. 196
  29. 100
  30. 7189
  31. 4761
  32. 1584
  33. 540
  34. 4096
  35. 34
  36. 225
  37. 289
  38. 8584
  39. 5
  40. 2844

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