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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 716 · 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 68².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 25².
  3. 3.If a − b = 1 and ab = 2, what is a² + b²?
  4. 4.Find the value of x² + 2xy + y² when x = 13 and y = 5.
  5. 5.Use a² − b² = (a + b)(a − b) to find 77² − 32².
  6. 6.If a + b = 4 and ab = 3, what is a² + b²?
  7. 7.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  8. 8.If a + b = 6 and ab = 5, what is a² + b²?
  9. 9.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 89².
  11. 11.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  12. 12.Use a² − b² = (a + b)(a − b) to find 95² − 6².
  13. 13.Use a² − b² = (a + b)(a − b) to find 42² − 11².
  14. 14.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  15. 15.Use (a + b)² = a² + 2ab + b² to find 72².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 48².
  17. 17.Use a² − b² = (a + b)(a − b) to find 25² − 15².
  18. 18.Find the value of x² − 2xy + y² when x = 4 and y = 3.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 33².
  20. 20.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  21. 21.If a + b = 6 and ab = 8, what is a² + b²?
  22. 22.Use (a + b)² = a² + 2ab + b² to find 101².
  23. 23.Use a² − b² = (a + b)(a − b) to find 39² − 22².
  24. 24.If a − b = 4 and ab = 12, what is a² + b²?
  25. 25.Use (a − b)² = a² − 2ab + b² to find 93².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 29².
  27. 27.Use a² − b² = (a + b)(a − b) to find 47² − 4².
  28. 28.If a − b = 3 and ab = 70, what is a² + b²?
  29. 29.Find the value of x² + 2xy + y² when x = 13 and y = 12.
  30. 30.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  31. 31.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  32. 32.Find the value of x² + 2xy + y² when x = 9 and y = 5.
  33. 33.If a − b = 7 and ab = 44, what is a² + b²?
  34. 34.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  35. 35.Use a² − b² = (a + b)(a − b) to find 20² − 8².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 95².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 34².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 28².
  39. 39.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 32².

Answer key

  1. 4624
  2. 625
  3. 5
  4. 324
  5. 4905
  6. 10
  7. 336
  8. 26
  9. 2436
  10. 7921
  11. 4
  12. 8989
  13. 1643
  14. 16
  15. 5184
  16. 2304
  17. 400
  18. 1
  19. 1089
  20. 9996
  21. 20
  22. 10201
  23. 1037
  24. 40
  25. 8649
  26. 841
  27. 2193
  28. 149
  29. 625
  30. 16
  31. 9975
  32. 196
  33. 137
  34. 3599
  35. 336
  36. 9025
  37. 1156
  38. 784
  39. 6351
  40. 1024

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