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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 110 · 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 85² − 4².
  2. 2.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  3. 3.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 23².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 44².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 44².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 88².
  8. 8.Use a² − b² = (a + b)(a − b) to find 98² − 32².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 17².
  10. 10.Use a² − b² = (a + b)(a − b) to find 60² − 44².
  11. 11.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  12. 12.If a − b = 10 and ab = 11, what is a² + b²?
  13. 13.Use a² − b² = (a + b)(a − b) to find 86² − 39².
  14. 14.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  15. 15.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  16. 16.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  17. 17.Find the value of x² + 2xy + y² when x = 7 and y = 1.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 12².
  19. 19.Use a² − b² = (a + b)(a − b) to find 23² − 6².
  20. 20.If a + b = 5 and ab = 4, what is a² + b²?
  21. 21.Find the value of x² − y² when x = 14 and y = 6.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 52².
  23. 23.Find the value of x² − 2xy + y² when x = 12 and y = 4.
  24. 24.Find the value of x² − 2xy + y² when x = 10 and y = 6.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 24².
  26. 26.Find the value of x² − 2xy + y² when x = 14 and y = 13.
  27. 27.Find the value of x² − 2xy + y² when x = 6 and y = 4.
  28. 28.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  29. 29.If a − b = 2 and ab = 8, what is a² + b²?
  30. 30.Find the value of x² − y² when x = 6 and y = 4.
  31. 31.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  32. 32.If a + b = 3 and ab = 2, what is a² + b²?
  33. 33.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  34. 34.Find the value of x² − y² when x = 3 and y = 1.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 38².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 13².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 69².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 65².
  39. 39.If a − b = 2 and ab = 3, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 99² − 45².

Answer key

  1. 7209
  2. 8084
  3. 4875
  4. 529
  5. 1936
  6. 1936
  7. 7744
  8. 8580
  9. 289
  10. 1664
  11. 391
  12. 122
  13. 5875
  14. 16
  15. 4891
  16. 16
  17. 64
  18. 144
  19. 493
  20. 17
  21. 160
  22. 2704
  23. 64
  24. 16
  25. 576
  26. 1
  27. 4
  28. 1
  29. 20
  30. 20
  31. 2436
  32. 5
  33. 4851
  34. 8
  35. 1444
  36. 169
  37. 4761
  38. 4225
  39. 10
  40. 7776

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