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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 466 · 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 = 5 and y = 2.
  2. 2.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 12².
  4. 4.Use a² − b² = (a + b)(a − b) to find 23² − 7².
  5. 5.If a + b = 12 and ab = 27, what is a² + b²?
  6. 6.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  7. 7.Use (a + b)² = a² + 2ab + b² to find 15².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 101².
  9. 9.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  10. 10.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  11. 11.Use a² − b² = (a + b)(a − b) to find 59² − 41².
  12. 12.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  13. 13.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  14. 14.Find the value of x² − y² when x = 12 and y = 2.
  15. 15.If a − b = 1 and ab = 90, what is a² + b²?
  16. 16.If a − b = 4 and ab = 60, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 74².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 92².
  19. 19.Use a² − b² = (a + b)(a − b) to find 50² − 9².
  20. 20.Use a² − b² = (a + b)(a − b) to find 85² − 6².
  21. 21.Use a² − b² = (a + b)(a − b) to find 72² − 40².
  22. 22.If a + b = 16 and ab = 55, what is a² + b²?
  23. 23.If a − b = 2 and ab = 120, what is a² + b²?
  24. 24.Find the value of x² − y² when x = 11 and y = 8.
  25. 25.Use a² − b² = (a + b)(a − b) to find 99² − 70².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 11².
  27. 27.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  28. 28.Use a² − b² = (a + b)(a − b) to find 75² − 65².
  29. 29.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  30. 30.Use a² − b² = (a + b)(a − b) to find 36² − 19².
  31. 31.If a − b = 3 and ab = 54, what is a² + b²?
  32. 32.If a + b = 5 and ab = 6, what is a² + b²?
  33. 33.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 71².
  35. 35.Use a² − b² = (a + b)(a − b) to find 81² − 53².
  36. 36.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 21².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 13².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 98².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 23².

Answer key

  1. 9
  2. 4
  3. 144
  4. 480
  5. 90
  6. 2484
  7. 225
  8. 10201
  9. 1584
  10. 25
  11. 1800
  12. 8091
  13. 3599
  14. 140
  15. 181
  16. 136
  17. 5476
  18. 8464
  19. 2419
  20. 7189
  21. 3584
  22. 146
  23. 244
  24. 57
  25. 4901
  26. 121
  27. 4896
  28. 1400
  29. 9991
  30. 935
  31. 117
  32. 13
  33. 2499
  34. 5041
  35. 3752
  36. 864
  37. 441
  38. 169
  39. 9604
  40. 529

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