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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 718 · 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 69².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 28².
  3. 3.Use a² − b² = (a + b)(a − b) to find 70² − 30².
  4. 4.If a − b = 1 and ab = 30, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 29².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 16².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 74².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 72².
  9. 9.If a + b = 17 and ab = 72, what is a² + b²?
  10. 10.If a − b = 4 and ab = 12, what is a² + b²?
  11. 11.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  12. 12.Use a² − b² = (a + b)(a − b) to find 78² − 53².
  13. 13.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  14. 14.Use a² − b² = (a + b)(a − b) to find 38² − 34².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 27².
  16. 16.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  17. 17.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  18. 18.Find the value of x² − y² when x = 5 and y = 1.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 25².
  20. 20.Find the value of x² − 2xy + y² when x = 11 and y = 1.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 56².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 96².
  23. 23.Find the value of x² + 2xy + y² when x = 8 and y = 5.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 84².
  25. 25.If a − b = 7 and ab = 18, what is a² + b²?
  26. 26.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  27. 27.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  28. 28.Find the value of x² − y² when x = 11 and y = 9.
  29. 29.If a + b = 13 and ab = 40, what is a² + b²?
  30. 30.Use (a + b)² = a² + 2ab + b² to find 73².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 82².
  32. 32.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  33. 33.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  34. 34.Use a² − b² = (a + b)(a − b) to find 92² − 72².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 23².
  36. 36.Find the value of x² + 2xy + y² when x = 8 and y = 6.
  37. 37.Use a² − b² = (a + b)(a − b) to find 33² − 20².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 95².
  39. 39.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 32².

Answer key

  1. 4761
  2. 784
  3. 4000
  4. 61
  5. 841
  6. 256
  7. 5476
  8. 5184
  9. 145
  10. 40
  11. 9964
  12. 3275
  13. 9
  14. 288
  15. 729
  16. 8084
  17. 4891
  18. 24
  19. 625
  20. 100
  21. 3136
  22. 9216
  23. 169
  24. 7056
  25. 85
  26. 6364
  27. 36
  28. 40
  29. 89
  30. 5329
  31. 6724
  32. 225
  33. 864
  34. 3280
  35. 529
  36. 196
  37. 689
  38. 9025
  39. 4
  40. 1024

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