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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 707 · 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 56 × 44.
  2. 2.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  3. 3.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  4. 4.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  5. 5.Find the value of x² − 2xy + y² when x = 11 and y = 2.
  6. 6.Find the value of x² − 2xy + y² when x = 10 and y = 6.
  7. 7.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  8. 8.Use a² − b² = (a + b)(a − b) to find 85² − 40².
  9. 9.If a − b = 9 and ab = 10, what is a² + b²?
  10. 10.Use (a + b)² = a² + 2ab + b² to find 59².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 23².
  12. 12.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 26².
  14. 14.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 99².
  16. 16.Use a² − b² = (a + b)(a − b) to find 27² − 4².
  17. 17.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  18. 18.If a − b = 3 and ab = 4, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 52².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 14².
  21. 21.Find the value of x² − y² when x = 3 and y = 1.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 98².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 18².
  24. 24.Find the value of x² − y² when x = 8 and y = 1.
  25. 25.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 38².
  27. 27.If a − b = 2 and ab = 15, what is a² + b²?
  28. 28.Use (a − b)² = a² − 2ab + b² to find 44².
  29. 29.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  30. 30.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  31. 31.Use a² − b² = (a + b)(a − b) to find 71² − 39².
  32. 32.If a + b = 10 and ab = 16, what is a² + b²?
  33. 33.If a − b = 5 and ab = 6, what is a² + b²?
  34. 34.Use (a − b)² = a² − 2ab + b² to find 11².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 92².
  36. 36.Use a² − b² = (a + b)(a − b) to find 93² − 29².
  37. 37.Use a² − b² = (a + b)(a − b) to find 59² − 32².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 89².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 56².
  40. 40.If a − b = 2 and ab = 63, what is a² + b²?

Answer key

  1. 2464
  2. 875
  3. 6364
  4. 6399
  5. 81
  6. 16
  7. 851
  8. 5625
  9. 101
  10. 3481
  11. 529
  12. 391
  13. 676
  14. 891
  15. 9801
  16. 713
  17. 899
  18. 17
  19. 2704
  20. 196
  21. 8
  22. 9604
  23. 324
  24. 63
  25. 4899
  26. 1444
  27. 34
  28. 1936
  29. 1551
  30. 8091
  31. 3520
  32. 68
  33. 37
  34. 121
  35. 8464
  36. 7808
  37. 2457
  38. 7921
  39. 3136
  40. 130

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