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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 65 · 40 sums
TalentJR

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.If a + b = 7 and ab = 10, what is a² + b²?
  2. 2.Find the value of x² − 2xy + y² when x = 6 and y = 2.
  3. 3.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  4. 4.Use a² − b² = (a + b)(a − b) to find 83² − 71².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 26².
  6. 6.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  7. 7.Use a² − b² = (a + b)(a − b) to find 69² − 48².
  8. 8.Find the value of x² − 2xy + y² when x = 10 and y = 1.
  9. 9.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  10. 10.Use a² − b² = (a + b)(a − b) to find 40² − 9².
  11. 11.Find the value of x² − y² when x = 10 and y = 9.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 36².
  13. 13.If a + b = 7 and ab = 12, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  15. 15.Use (a + b)² = a² + 2ab + b² to find 14².
  16. 16.If a + b = 6 and ab = 5, what is a² + b²?
  17. 17.Use (a + b)² = a² + 2ab + b² to find 18².
  18. 18.Find the value of x² − 2xy + y² when x = 10 and y = 4.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 49².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 48².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 101².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 43².
  23. 23.If a − b = 8 and ab = 33, what is a² + b²?
  24. 24.Use (a − b)² = a² − 2ab + b² to find 42².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 37².
  26. 26.If a − b = 2 and ab = 35, what is a² + b²?
  27. 27.Use a² − b² = (a + b)(a − b) to find 75² − 24².
  28. 28.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  29. 29.Find the value of x² − y² when x = 9 and y = 2.
  30. 30.If a + b = 13 and ab = 40, what is a² + b²?
  31. 31.Use a² − b² = (a + b)(a − b) to find 63² − 42².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 34².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 34².
  34. 34.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 21².
  36. 36.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 94².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 58².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 71².
  40. 40.Use a² − b² = (a + b)(a − b) to find 73² − 19².

Answer key

  1. 29
  2. 16
  3. 6364
  4. 1848
  5. 676
  6. 6384
  7. 2457
  8. 81
  9. 1575
  10. 1519
  11. 19
  12. 1296
  13. 25
  14. 1591
  15. 196
  16. 26
  17. 324
  18. 36
  19. 2401
  20. 2304
  21. 10201
  22. 1849
  23. 130
  24. 1764
  25. 1369
  26. 74
  27. 5049
  28. 836
  29. 77
  30. 89
  31. 2205
  32. 1156
  33. 1156
  34. 49
  35. 441
  36. 81
  37. 8836
  38. 3364
  39. 5041
  40. 4968

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