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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 324 · 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 − y² when x = 7 and y = 3.
  2. 2.Find the value of x² + 2xy + y² when x = 12 and y = 11.
  3. 3.Find the value of x² + 2xy + y² when x = 9 and y = 8.
  4. 4.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  5. 5.If a + b = 7 and ab = 12, what is a² + b²?
  6. 6.Find the value of x² − 2xy + y² when x = 5 and y = 2.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 19².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 23².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 57².
  10. 10.If a + b = 11 and ab = 18, what is a² + b²?
  11. 11.If a + b = 21 and ab = 110, what is a² + b²?
  12. 12.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  13. 13.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 59².
  15. 15.If a + b = 11 and ab = 24, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 18².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 73².
  18. 18.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  19. 19.If a + b = 4 and ab = 3, what is a² + b²?
  20. 20.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  21. 21.Use a² − b² = (a + b)(a − b) to find 63² − 22².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 78².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 18².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 79².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 56².
  26. 26.Find the value of x² + 2xy + y² when x = 10 and y = 3.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 24².
  28. 28.Find the value of x² − y² when x = 9 and y = 2.
  29. 29.If a + b = 5 and ab = 6, what is a² + b²?
  30. 30.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  31. 31.Use a² − b² = (a + b)(a − b) to find 35² − 24².
  32. 32.If a − b = 2 and ab = 63, what is a² + b²?
  33. 33.If a + b = 8 and ab = 12, what is a² + b²?
  34. 34.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  35. 35.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  36. 36.Use a² − b² = (a + b)(a − b) to find 72² − 53².
  37. 37.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  38. 38.Find the value of x² + 2xy + y² when x = 11 and y = 7.
  39. 39.Find the value of x² + 2xy + y² when x = 11 and y = 4.
  40. 40.Use (a + b)(a − b) = a² − b² to find 46 × 34.

Answer key

  1. 40
  2. 529
  3. 289
  4. 2491
  5. 25
  6. 9
  7. 361
  8. 529
  9. 3249
  10. 85
  11. 221
  12. 2436
  13. 6391
  14. 3481
  15. 73
  16. 324
  17. 5329
  18. 1551
  19. 10
  20. 25
  21. 3485
  22. 6084
  23. 324
  24. 6241
  25. 3136
  26. 169
  27. 576
  28. 77
  29. 13
  30. 884
  31. 649
  32. 130
  33. 40
  34. 6396
  35. 49
  36. 2375
  37. 9
  38. 324
  39. 225
  40. 1564

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