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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 977 · 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)(a − b) = a² − b² to find 33 × 27.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 14².
  3. 3.Use a² − b² = (a + b)(a − b) to find 36² − 13².
  4. 4.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  5. 5.Use (a − b)² = a² − 2ab + b² to find 97².
  6. 6.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  7. 7.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  8. 8.If a − b = 9 and ab = 36, what is a² + b²?
  9. 9.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 49².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 76².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 48².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 12².
  14. 14.Find the value of x² − y² when x = 15 and y = 12.
  15. 15.If a − b = 5 and ab = 36, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 39².
  17. 17.Find the value of x² − y² when x = 4 and y = 3.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 89².
  19. 19.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  20. 20.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  21. 21.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  22. 22.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  23. 23.Use a² − b² = (a + b)(a − b) to find 30² − 21².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 99².
  25. 25.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  26. 26.If a − b = 2 and ab = 80, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 39².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 67².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 13².
  30. 30.Find the value of x² + 2xy + y² when x = 14 and y = 4.
  31. 31.Find the value of x² − 2xy + y² when x = 13 and y = 7.
  32. 32.Use a² − b² = (a + b)(a − b) to find 35² − 29².
  33. 33.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  34. 34.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 38².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 33².
  37. 37.Use a² − b² = (a + b)(a − b) to find 53² − 48².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 26².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 37².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 85².

Answer key

  1. 891
  2. 196
  3. 1127
  4. 884
  5. 9409
  6. 1536
  7. 3551
  8. 153
  9. 4819
  10. 2401
  11. 5776
  12. 2304
  13. 144
  14. 81
  15. 97
  16. 1521
  17. 7
  18. 7921
  19. 49
  20. 9999
  21. 16
  22. 2464
  23. 459
  24. 9801
  25. 144
  26. 164
  27. 1521
  28. 4489
  29. 169
  30. 324
  31. 36
  32. 384
  33. 1591
  34. 6319
  35. 1444
  36. 1089
  37. 505
  38. 676
  39. 1369
  40. 7225

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