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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 481 · 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.If a − b = 4 and ab = 5, what is a² + b²?
  2. 2.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 44².
  4. 4.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  5. 5.Use a² − b² = (a + b)(a − b) to find 36² − 20².
  6. 6.If a − b = 4 and ab = 45, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 98².
  8. 8.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  9. 9.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  10. 10.Find the value of x² − 2xy + y² when x = 12 and y = 3.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 81².
  12. 12.Find the value of x² − y² when x = 9 and y = 4.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 53².
  14. 14.If a + b = 6 and ab = 8, what is a² + b²?
  15. 15.Use a² − b² = (a + b)(a − b) to find 68² − 54².
  16. 16.Use a² − b² = (a + b)(a − b) to find 55² − 49².
  17. 17.If a − b = 2 and ab = 24, what is a² + b²?
  18. 18.If a − b = 3 and ab = 4, what is a² + b²?
  19. 19.Find the value of x² + 2xy + y² when x = 14 and y = 6.
  20. 20.If a + b = 5 and ab = 6, what is a² + b²?
  21. 21.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  22. 22.Use a² − b² = (a + b)(a − b) to find 63² − 43².
  23. 23.Find the value of x² + 2xy + y² when x = 8 and y = 5.
  24. 24.Use a² − b² = (a + b)(a − b) to find 39² − 26².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 57².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 91².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 64².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 86².
  29. 29.Use a² − b² = (a + b)(a − b) to find 72² − 54².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 63².
  31. 31.If a + b = 10 and ab = 21, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 29² − 26².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 34².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 18².
  35. 35.Use a² − b² = (a + b)(a − b) to find 36² − 29².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 88².
  37. 37.If a + b = 13 and ab = 36, what is a² + b²?
  38. 38.Use (a + b)² = a² + 2ab + b² to find 84².
  39. 39.If a − b = 1 and ab = 2, what is a² + b²?
  40. 40.Use (a + b)² = a² + 2ab + b² to find 95².

Answer key

  1. 26
  2. 1536
  3. 1936
  4. 2419
  5. 896
  6. 106
  7. 9604
  8. 4819
  9. 4
  10. 81
  11. 6561
  12. 65
  13. 2809
  14. 20
  15. 1708
  16. 624
  17. 52
  18. 17
  19. 400
  20. 13
  21. 875
  22. 2120
  23. 169
  24. 845
  25. 3249
  26. 8281
  27. 4096
  28. 7396
  29. 2268
  30. 3969
  31. 58
  32. 165
  33. 1156
  34. 324
  35. 455
  36. 7744
  37. 97
  38. 7056
  39. 5
  40. 9025

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