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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 490 · 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.Find the value of x² − y² when x = 9 and y = 2.
  2. 2.Find the value of x² − y² when x = 3 and y = 2.
  3. 3.Find the value of x² − y² when x = 5 and y = 3.
  4. 4.Find the value of x² + 2xy + y² when x = 13 and y = 2.
  5. 5.Find the value of x² − y² when x = 6 and y = 5.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 37².
  7. 7.Find the value of x² − y² when x = 7 and y = 4.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 41².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 81².
  10. 10.If a − b = 1 and ab = 6, what is a² + b²?
  11. 11.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  12. 12.Find the value of x² − y² when x = 14 and y = 13.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 62².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 17².
  15. 15.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  16. 16.Find the value of x² + 2xy + y² when x = 12 and y = 1.
  17. 17.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  18. 18.If a + b = 12 and ab = 35, what is a² + b²?
  19. 19.Find the value of x² − y² when x = 11 and y = 9.
  20. 20.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  21. 21.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 71².
  23. 23.Use a² − b² = (a + b)(a − b) to find 61² − 5².
  24. 24.If a + b = 5 and ab = 6, what is a² + b²?
  25. 25.Use (a − b)² = a² − 2ab + b² to find 73².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 99².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 34².
  28. 28.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  29. 29.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  30. 30.Use a² − b² = (a + b)(a − b) to find 65² − 38².
  31. 31.Find the value of x² − y² when x = 13 and y = 2.
  32. 32.Use (a + b)² = a² + 2ab + b² to find 54².
  33. 33.If a − b = 2 and ab = 120, what is a² + b²?
  34. 34.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  35. 35.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  36. 36.If a − b = 1 and ab = 20, what is a² + b²?
  37. 37.Use (a + b)² = a² + 2ab + b² to find 96².
  38. 38.Use a² − b² = (a + b)(a − b) to find 81² − 56².
  39. 39.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  40. 40.Find the value of x² + 2xy + y² when x = 7 and y = 2.

Answer key

  1. 77
  2. 5
  3. 16
  4. 225
  5. 11
  6. 1369
  7. 33
  8. 1681
  9. 6561
  10. 13
  11. 9951
  12. 27
  13. 3844
  14. 289
  15. 3596
  16. 169
  17. 36
  18. 74
  19. 40
  20. 875
  21. 3536
  22. 5041
  23. 3696
  24. 13
  25. 5329
  26. 9801
  27. 1156
  28. 891
  29. 2419
  30. 2781
  31. 165
  32. 2916
  33. 244
  34. 8036
  35. 2436
  36. 41
  37. 9216
  38. 3425
  39. 25
  40. 81

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