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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 287 · 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 − 2xy + y² when x = 9 and y = 5.
  2. 2.Find the value of x² + 2xy + y² when x = 13 and y = 2.
  3. 3.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  4. 4.Find the value of x² − y² when x = 5 and y = 4.
  5. 5.Find the value of x² − 2xy + y² when x = 15 and y = 8.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 59².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 72².
  8. 8.If a + b = 11 and ab = 24, what is a² + b²?
  9. 9.If a + b = 8 and ab = 15, what is a² + b²?
  10. 10.Use (a + b)² = a² + 2ab + b² to find 52².
  11. 11.Find the value of x² + 2xy + y² when x = 14 and y = 9.
  12. 12.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  13. 13.If a − b = 1 and ab = 2, what is a² + b²?
  14. 14.Use a² − b² = (a + b)(a − b) to find 92² − 54².
  15. 15.Use a² − b² = (a + b)(a − b) to find 71² − 44².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 65².
  17. 17.Find the value of x² + 2xy + y² when x = 10 and y = 4.
  18. 18.If a − b = 1 and ab = 6, what is a² + b²?
  19. 19.Use a² − b² = (a + b)(a − b) to find 90² − 54².
  20. 20.Find the value of x² − 2xy + y² when x = 11 and y = 2.
  21. 21.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  22. 22.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 44².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 102².
  25. 25.Use a² − b² = (a + b)(a − b) to find 52² − 29².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 32².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 75².
  28. 28.If a + b = 13 and ab = 42, what is a² + b²?
  29. 29.If a + b = 14 and ab = 24, what is a² + b²?
  30. 30.If a − b = 6 and ab = 72, what is a² + b²?
  31. 31.Use a² − b² = (a + b)(a − b) to find 63² − 33².
  32. 32.Use a² − b² = (a + b)(a − b) to find 33² − 11².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 89².
  34. 34.Use a² − b² = (a + b)(a − b) to find 83² − 2².
  35. 35.Use a² − b² = (a + b)(a − b) to find 49² − 17².
  36. 36.Find the value of x² − 2xy + y² when x = 12 and y = 4.
  37. 37.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  38. 38.Find the value of x² − 2xy + y² when x = 12 and y = 1.
  39. 39.Use a² − b² = (a + b)(a − b) to find 86² − 75².
  40. 40.If a + b = 5 and ab = 6, what is a² + b²?

Answer key

  1. 16
  2. 225
  3. 4819
  4. 9
  5. 49
  6. 3481
  7. 5184
  8. 73
  9. 34
  10. 2704
  11. 529
  12. 384
  13. 5
  14. 5548
  15. 3105
  16. 4225
  17. 196
  18. 13
  19. 5184
  20. 81
  21. 8019
  22. 9999
  23. 1936
  24. 10404
  25. 1863
  26. 1024
  27. 5625
  28. 85
  29. 148
  30. 180
  31. 2880
  32. 968
  33. 7921
  34. 6885
  35. 2112
  36. 64
  37. 896
  38. 121
  39. 1771
  40. 13

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