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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 405 · 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 a² − b² = (a + b)(a − b) to find 96² − 33².
  2. 2.Find the value of x² − y² when x = 12 and y = 9.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 13².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 27².
  5. 5.Find the value of x² − 2xy + y² when x = 12 and y = 5.
  6. 6.If a − b = 3 and ab = 4, what is a² + b²?
  7. 7.Find the value of x² + 2xy + y² when x = 7 and y = 4.
  8. 8.Use a² − b² = (a + b)(a − b) to find 55² − 53².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 74².
  10. 10.Find the value of x² − y² when x = 6 and y = 1.
  11. 11.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 32².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 91².
  14. 14.If a − b = 5 and ab = 66, what is a² + b²?
  15. 15.Use a² − b² = (a + b)(a − b) to find 41² − 36².
  16. 16.Use a² − b² = (a + b)(a − b) to find 25² − 1².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 99².
  18. 18.If a + b = 11 and ab = 30, what is a² + b²?
  19. 19.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  20. 20.If a + b = 17 and ab = 70, what is a² + b²?
  21. 21.Use a² − b² = (a + b)(a − b) to find 63² − 38².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 57².
  23. 23.Use a² − b² = (a + b)(a − b) to find 52² − 5².
  24. 24.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  25. 25.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 81².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 69².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 74².
  29. 29.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  30. 30.Find the value of x² − 2xy + y² when x = 13 and y = 9.
  31. 31.If a + b = 14 and ab = 48, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 72² − 70².
  33. 33.If a + b = 6 and ab = 8, what is a² + b²?
  34. 34.If a − b = 6 and ab = 72, what is a² + b²?
  35. 35.Use (a + b)² = a² + 2ab + b² to find 59².
  36. 36.Use a² − b² = (a + b)(a − b) to find 30² − 7².
  37. 37.If a − b = 1 and ab = 2, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 95².
  39. 39.Find the value of x² − y² when x = 12 and y = 2.
  40. 40.Use (a + b)(a − b) = a² − b² to find 26 × 14.

Answer key

  1. 8127
  2. 63
  3. 169
  4. 729
  5. 49
  6. 17
  7. 121
  8. 216
  9. 5476
  10. 35
  11. 1536
  12. 1024
  13. 8281
  14. 157
  15. 385
  16. 624
  17. 9801
  18. 61
  19. 8099
  20. 149
  21. 2525
  22. 3249
  23. 2679
  24. 8075
  25. 399
  26. 6561
  27. 4761
  28. 5476
  29. 2496
  30. 16
  31. 100
  32. 284
  33. 20
  34. 180
  35. 3481
  36. 851
  37. 5
  38. 9025
  39. 140
  40. 364

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