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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 109 · 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 23².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 31².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 81².
  4. 4.Use a² − b² = (a + b)(a − b) to find 56² − 46².
  5. 5.Use a² − b² = (a + b)(a − b) to find 37² − 3².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 19².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 12².
  8. 8.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  9. 9.Use a² − b² = (a + b)(a − b) to find 50² − 39².
  10. 10.Find the value of x² + 2xy + y² when x = 13 and y = 11.
  11. 11.If a + b = 17 and ab = 66, what is a² + b²?
  12. 12.Use (a − b)² = a² − 2ab + b² to find 95².
  13. 13.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  14. 14.Use a² − b² = (a + b)(a − b) to find 31² − 30².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 44².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 73².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 49².
  18. 18.Find the value of x² − y² when x = 9 and y = 3.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 14².
  20. 20.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 13².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 84².
  23. 23.Use a² − b² = (a + b)(a − b) to find 72² − 1².
  24. 24.Find the value of x² − 2xy + y² when x = 13 and y = 1.
  25. 25.Use a² − b² = (a + b)(a − b) to find 35² − 21².
  26. 26.If a + b = 13 and ab = 40, what is a² + b²?
  27. 27.If a − b = 2 and ab = 8, what is a² + b²?
  28. 28.Use a² − b² = (a + b)(a − b) to find 58² − 2².
  29. 29.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  30. 30.Use a² − b² = (a + b)(a − b) to find 96² − 88².
  31. 31.Use a² − b² = (a + b)(a − b) to find 21² − 4².
  32. 32.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 78².
  34. 34.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 34².
  36. 36.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 77².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 36².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 108².
  40. 40.Find the value of x² − 2xy + y² when x = 6 and y = 2.

Answer key

  1. 529
  2. 961
  3. 6561
  4. 1020
  5. 1360
  6. 361
  7. 144
  8. 3584
  9. 979
  10. 576
  11. 157
  12. 9025
  13. 2436
  14. 61
  15. 1936
  16. 5329
  17. 2401
  18. 72
  19. 196
  20. 6336
  21. 169
  22. 7056
  23. 5183
  24. 144
  25. 784
  26. 89
  27. 20
  28. 3360
  29. 4
  30. 1472
  31. 425
  32. 1575
  33. 6084
  34. 169
  35. 1156
  36. 319
  37. 5929
  38. 1296
  39. 11664
  40. 16

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