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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 974 · 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 103 × 97.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 29².
  3. 3.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 45².
  5. 5.Use a² − b² = (a + b)(a − b) to find 83² − 11².
  6. 6.Use a² − b² = (a + b)(a − b) to find 62² − 60².
  7. 7.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  8. 8.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 35².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 21².
  11. 11.If a + b = 19 and ab = 84, what is a² + b²?
  12. 12.Use (a + b)² = a² + 2ab + b² to find 59².
  13. 13.If a + b = 7 and ab = 12, what is a² + b²?
  14. 14.If a + b = 6 and ab = 8, what is a² + b²?
  15. 15.If a − b = 3 and ab = 28, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 67².
  17. 17.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  18. 18.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  19. 19.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  20. 20.Use a² − b² = (a + b)(a − b) to find 86² − 39².
  21. 21.Find the value of x² − y² when x = 6 and y = 1.
  22. 22.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  23. 23.Find the value of x² − 2xy + y² when x = 15 and y = 9.
  24. 24.If a − b = 2 and ab = 63, what is a² + b²?
  25. 25.Find the value of x² + 2xy + y² when x = 12 and y = 8.
  26. 26.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  27. 27.Use a² − b² = (a + b)(a − b) to find 91² − 49².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 34².
  29. 29.If a − b = 4 and ab = 5, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 43² − 11².
  31. 31.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  32. 32.If a + b = 3 and ab = 2, what is a² + b²?
  33. 33.Use (a + b)² = a² + 2ab + b² to find 67².
  34. 34.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  35. 35.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 95².
  37. 37.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  38. 38.Use a² − b² = (a + b)(a − b) to find 55² − 1².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 17².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 28².

Answer key

  1. 9991
  2. 841
  3. 891
  4. 2025
  5. 6768
  6. 244
  7. 2484
  8. 1591
  9. 1225
  10. 441
  11. 193
  12. 3481
  13. 25
  14. 20
  15. 65
  16. 4489
  17. 399
  18. 896
  19. 3584
  20. 5875
  21. 35
  22. 49
  23. 36
  24. 130
  25. 400
  26. 3599
  27. 5880
  28. 1156
  29. 26
  30. 1728
  31. 319
  32. 5
  33. 4489
  34. 875
  35. 4891
  36. 9025
  37. 144
  38. 3024
  39. 289
  40. 784

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