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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 524 · 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 63².
  2. 2.If a + b = 7 and ab = 6, what is a² + b²?
  3. 3.Use (a − b)² = a² − 2ab + b² to find 16².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 97².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 25².
  6. 6.Use a² − b² = (a + b)(a − b) to find 50² − 16².
  7. 7.Find the value of x² + 2xy + y² when x = 8 and y = 2.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 96².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 91².
  10. 10.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 72².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 87².
  13. 13.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  14. 14.Find the value of x² + 2xy + y² when x = 9 and y = 2.
  15. 15.Find the value of x² + 2xy + y² when x = 11 and y = 2.
  16. 16.Find the value of x² − 2xy + y² when x = 9 and y = 7.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 49².
  18. 18.Find the value of x² − 2xy + y² when x = 12 and y = 10.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 29².
  20. 20.Use a² − b² = (a + b)(a − b) to find 43² − 18².
  21. 21.Find the value of x² + 2xy + y² when x = 15 and y = 3.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 39².
  23. 23.Use a² − b² = (a + b)(a − b) to find 36² − 17².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 42².
  25. 25.If a + b = 16 and ab = 63, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 43².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 24².
  28. 28.If a + b = 15 and ab = 44, what is a² + b²?
  29. 29.Use (a − b)² = a² − 2ab + b² to find 14².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 47².
  31. 31.If a + b = 20 and ab = 99, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 54² − 38².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 82².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 86².
  35. 35.Use a² − b² = (a + b)(a − b) to find 91² − 12².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 62².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 44².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 82².
  39. 39.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  40. 40.Find the value of x² − y² when x = 10 and y = 9.

Answer key

  1. 3969
  2. 37
  3. 256
  4. 9409
  5. 625
  6. 2244
  7. 100
  8. 9216
  9. 8281
  10. 1599
  11. 5184
  12. 7569
  13. 8075
  14. 121
  15. 169
  16. 4
  17. 2401
  18. 4
  19. 841
  20. 1525
  21. 324
  22. 1521
  23. 1007
  24. 1764
  25. 130
  26. 1849
  27. 576
  28. 137
  29. 196
  30. 2209
  31. 202
  32. 1472
  33. 6724
  34. 7396
  35. 8137
  36. 3844
  37. 1936
  38. 6724
  39. 8096
  40. 19

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