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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 918 · 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)(a − b) = a² − b² to find 24 × 16.
  2. 2.Use a² − b² = (a + b)(a − b) to find 47² − 18².
  3. 3.If a − b = 6 and ab = 72, what is a² + b²?
  4. 4.Use (a − b)² = a² − 2ab + b² to find 63².
  5. 5.Use a² − b² = (a + b)(a − b) to find 93² − 41².
  6. 6.Use a² − b² = (a + b)(a − b) to find 55² − 28².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 57².
  8. 8.Use a² − b² = (a + b)(a − b) to find 75² − 31².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 31².
  10. 10.If a + b = 5 and ab = 6, what is a² + b²?
  11. 11.Find the value of x² − 2xy + y² when x = 15 and y = 11.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 16².
  13. 13.Use a² − b² = (a + b)(a − b) to find 91² − 25².
  14. 14.Use a² − b² = (a + b)(a − b) to find 38² − 15².
  15. 15.Find the value of x² − y² when x = 13 and y = 4.
  16. 16.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 58².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 26².
  19. 19.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  20. 20.Use (a + b)² = a² + 2ab + b² to find 17².
  21. 21.Use a² − b² = (a + b)(a − b) to find 35² − 7².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 69².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 91².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 33².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 23².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 73².
  27. 27.If a + b = 4 and ab = 3, what is a² + b²?
  28. 28.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  29. 29.Use a² − b² = (a + b)(a − b) to find 41² − 33².
  30. 30.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  31. 31.If a − b = 7 and ab = 60, what is a² + b²?
  32. 32.Use (a − b)² = a² − 2ab + b² to find 82².
  33. 33.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  34. 34.Use a² − b² = (a + b)(a − b) to find 47² − 34².
  35. 35.Find the value of x² + 2xy + y² when x = 9 and y = 2.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 98².
  37. 37.Use a² − b² = (a + b)(a − b) to find 85² − 16².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 62².
  39. 39.If a − b = 4 and ab = 5, what is a² + b²?
  40. 40.Use (a − b)² = a² − 2ab + b² to find 72².

Answer key

  1. 384
  2. 1885
  3. 180
  4. 3969
  5. 6968
  6. 2241
  7. 3249
  8. 4664
  9. 961
  10. 13
  11. 16
  12. 256
  13. 7656
  14. 1219
  15. 153
  16. 49
  17. 3364
  18. 676
  19. 25
  20. 289
  21. 1176
  22. 4761
  23. 8281
  24. 1089
  25. 529
  26. 5329
  27. 10
  28. 64
  29. 592
  30. 4896
  31. 169
  32. 6724
  33. 891
  34. 1053
  35. 121
  36. 9604
  37. 6969
  38. 3844
  39. 26
  40. 5184

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