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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 769 · 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.Use (a − b)² = a² − 2ab + b² to find 69².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 91².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 53².
  4. 4.If a + b = 14 and ab = 40, what is a² + b²?
  5. 5.Find the value of x² − 2xy + y² when x = 8 and y = 4.
  6. 6.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  7. 7.Find the value of x² − 2xy + y² when x = 7 and y = 6.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 35².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 68².
  10. 10.If a − b = 5 and ab = 6, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 81² − 10².
  12. 12.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  13. 13.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  14. 14.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  15. 15.Find the value of x² − y² when x = 4 and y = 2.
  16. 16.Find the value of x² − 2xy + y² when x = 14 and y = 10.
  17. 17.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  18. 18.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 62².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 92².
  21. 21.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  22. 22.Use a² − b² = (a + b)(a − b) to find 91² − 43².
  23. 23.If a − b = 4 and ab = 5, what is a² + b²?
  24. 24.Use (a − b)² = a² − 2ab + b² to find 72².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 18².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 99².
  27. 27.Find the value of x² + 2xy + y² when x = 9 and y = 5.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 33².
  29. 29.Find the value of x² − y² when x = 9 and y = 4.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 77².
  31. 31.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  32. 32.If a + b = 16 and ab = 48, what is a² + b²?
  33. 33.Use (a + b)² = a² + 2ab + b² to find 33².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 23².
  35. 35.Find the value of x² + 2xy + y² when x = 15 and y = 14.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 37².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 105².
  38. 38.Use a² − b² = (a + b)(a − b) to find 62² − 35².
  39. 39.Find the value of x² − y² when x = 12 and y = 10.
  40. 40.Use a² − b² = (a + b)(a − b) to find 95² − 25².

Answer key

  1. 4761
  2. 8281
  3. 2809
  4. 116
  5. 16
  6. 884
  7. 1
  8. 1225
  9. 4624
  10. 37
  11. 6461
  12. 375
  13. 8064
  14. 2436
  15. 12
  16. 16
  17. 2491
  18. 1584
  19. 3844
  20. 8464
  21. 9999
  22. 6432
  23. 26
  24. 5184
  25. 324
  26. 9801
  27. 196
  28. 1089
  29. 65
  30. 5929
  31. 396
  32. 160
  33. 1089
  34. 529
  35. 841
  36. 1369
  37. 11025
  38. 2619
  39. 44
  40. 8400

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