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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 33 · 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.Find the value of x² + 2xy + y² when x = 8 and y = 5.
  2. 2.Find the value of x² − y² when x = 11 and y = 4.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 91².
  4. 4.Find the value of x² − 2xy + y² when x = 9 and y = 1.
  5. 5.Use (a − b)² = a² − 2ab + b² to find 48².
  6. 6.Use a² − b² = (a + b)(a − b) to find 98² − 78².
  7. 7.Use a² − b² = (a + b)(a − b) to find 72² − 52².
  8. 8.Use a² − b² = (a + b)(a − b) to find 61² − 39².
  9. 9.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 24².
  11. 11.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  12. 12.Use a² − b² = (a + b)(a − b) to find 67² − 18².
  13. 13.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 41².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 97².
  16. 16.Find the value of x² − y² when x = 13 and y = 4.
  17. 17.If a + b = 11 and ab = 30, what is a² + b²?
  18. 18.Use (a + b)² = a² + 2ab + b² to find 101².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 42².
  20. 20.Use a² − b² = (a + b)(a − b) to find 58² − 12².
  21. 21.Find the value of x² + 2xy + y² when x = 13 and y = 10.
  22. 22.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 38².
  24. 24.Find the value of x² − 2xy + y² when x = 14 and y = 7.
  25. 25.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 93².
  27. 27.Find the value of x² − y² when x = 9 and y = 2.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 74².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 44².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 13².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 58².
  32. 32.Use a² − b² = (a + b)(a − b) to find 45² − 22².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 68².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 47².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 15².
  36. 36.If a − b = 1 and ab = 2, what is a² + b²?
  37. 37.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  38. 38.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  39. 39.If a + b = 14 and ab = 24, what is a² + b²?
  40. 40.Use (a − b)² = a² − 2ab + b² to find 89².

Answer key

  1. 169
  2. 105
  3. 8281
  4. 64
  5. 2304
  6. 3520
  7. 2480
  8. 2200
  9. 1536
  10. 576
  11. 1
  12. 4165
  13. 8084
  14. 1681
  15. 9409
  16. 153
  17. 61
  18. 10201
  19. 1764
  20. 3220
  21. 529
  22. 9984
  23. 1444
  24. 49
  25. 851
  26. 8649
  27. 77
  28. 5476
  29. 1936
  30. 169
  31. 3364
  32. 1541
  33. 4624
  34. 2209
  35. 225
  36. 5
  37. 875
  38. 9975
  39. 148
  40. 7921

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