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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 513 · 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 = 10 and y = 7.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 72².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 25².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 74².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 86².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 13².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 31².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 23².
  9. 9.Use a² − b² = (a + b)(a − b) to find 48² − 32².
  10. 10.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 108².
  12. 12.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  13. 13.Use a² − b² = (a + b)(a − b) to find 39² − 11².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 29².
  15. 15.Find the value of x² − y² when x = 13 and y = 5.
  16. 16.If a + b = 10 and ab = 9, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 28².
  18. 18.Use a² − b² = (a + b)(a − b) to find 58² − 44².
  19. 19.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  20. 20.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 29².
  22. 22.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  23. 23.Use (a − b)² = a² − 2ab + b² to find 66².
  24. 24.Use (a + b)(a − b) = a² − b² to find 108 × 92.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 56².
  26. 26.Find the value of x² − 2xy + y² when x = 9 and y = 1.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 62².
  28. 28.If a − b = 1 and ab = 2, what is a² + b²?
  29. 29.If a + b = 5 and ab = 6, what is a² + b²?
  30. 30.Use (a − b)² = a² − 2ab + b² to find 45².
  31. 31.If a − b = 1 and ab = 30, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 76² − 63².
  33. 33.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  34. 34.If a − b = 3 and ab = 88, what is a² + b²?
  35. 35.Use (a − b)² = a² − 2ab + b² to find 33².
  36. 36.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  37. 37.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  38. 38.Find the value of x² − 2xy + y² when x = 15 and y = 12.
  39. 39.Use a² − b² = (a + b)(a − b) to find 49² − 24².
  40. 40.If a − b = 1 and ab = 6, what is a² + b²?

Answer key

  1. 289
  2. 5184
  3. 625
  4. 5476
  5. 7396
  6. 169
  7. 961
  8. 529
  9. 1280
  10. 3596
  11. 11664
  12. 3519
  13. 1400
  14. 841
  15. 144
  16. 82
  17. 784
  18. 1428
  19. 4884
  20. 2475
  21. 841
  22. 6399
  23. 4356
  24. 9936
  25. 3136
  26. 64
  27. 3844
  28. 5
  29. 13
  30. 2025
  31. 61
  32. 1807
  33. 875
  34. 185
  35. 1089
  36. 9996
  37. 1591
  38. 9
  39. 1825
  40. 13

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