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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 958 · 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 61².
  2. 2.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  3. 3.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 22².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 38².
  6. 6.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  7. 7.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  8. 8.Find the value of x² − 2xy + y² when x = 9 and y = 1.
  9. 9.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 72².
  11. 11.If a + b = 17 and ab = 60, what is a² + b²?
  12. 12.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  13. 13.If a − b = 5 and ab = 6, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 13².
  15. 15.Find the value of x² + 2xy + y² when x = 6 and y = 4.
  16. 16.Use a² − b² = (a + b)(a − b) to find 60² − 24².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 85².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 71².
  19. 19.Use a² − b² = (a + b)(a − b) to find 65² − 35².
  20. 20.Find the value of x² − 2xy + y² when x = 7 and y = 3.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 91².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 27².
  23. 23.Find the value of x² + 2xy + y² when x = 15 and y = 7.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 91².
  25. 25.If a − b = 1 and ab = 6, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 14².
  27. 27.Use a² − b² = (a + b)(a − b) to find 37² − 26².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 52².
  29. 29.Use a² − b² = (a + b)(a − b) to find 84² − 9².
  30. 30.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  31. 31.If a + b = 3 and ab = 2, what is a² + b²?
  32. 32.Use (a − b)² = a² − 2ab + b² to find 31².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 56².
  34. 34.If a + b = 10 and ab = 24, what is a² + b²?
  35. 35.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  36. 36.Find the value of x² − 2xy + y² when x = 11 and y = 10.
  37. 37.Find the value of x² − 2xy + y² when x = 11 and y = 3.
  38. 38.Use a² − b² = (a + b)(a − b) to find 77² − 68².
  39. 39.If a − b = 4 and ab = 32, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 98² − 96².

Answer key

  1. 3721
  2. 391
  3. 2491
  4. 484
  5. 1444
  6. 8091
  7. 899
  8. 64
  9. 3519
  10. 5184
  11. 169
  12. 2436
  13. 37
  14. 169
  15. 100
  16. 3024
  17. 7225
  18. 5041
  19. 3000
  20. 16
  21. 8281
  22. 729
  23. 484
  24. 8281
  25. 13
  26. 196
  27. 693
  28. 2704
  29. 6975
  30. 6336
  31. 5
  32. 961
  33. 3136
  34. 52
  35. 351
  36. 1
  37. 64
  38. 1305
  39. 80
  40. 388

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