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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 454 · 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)² = a² − 2ab + b² to find 16².
  2. 2.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  3. 3.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  4. 4.Find the value of x² + 2xy + y² when x = 11 and y = 3.
  5. 5.Use (a − b)² = a² − 2ab + b² to find 79².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 14².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 104².
  8. 8.Find the value of x² − 2xy + y² when x = 7 and y = 5.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 105².
  10. 10.If a + b = 9 and ab = 18, what is a² + b²?
  11. 11.Use (a + b)² = a² + 2ab + b² to find 73².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 96².
  13. 13.If a − b = 5 and ab = 66, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 61².
  15. 15.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  16. 16.Use a² − b² = (a + b)(a − b) to find 91² − 56².
  17. 17.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  18. 18.Find the value of x² − y² when x = 14 and y = 3.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 75².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 37².
  21. 21.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  22. 22.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  23. 23.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  24. 24.Use a² − b² = (a + b)(a − b) to find 65² − 8².
  25. 25.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  26. 26.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  27. 27.Find the value of x² − y² when x = 5 and y = 4.
  28. 28.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 84².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 63².
  31. 31.If a − b = 6 and ab = 27, what is a² + b²?
  32. 32.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 43².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 63².
  35. 35.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  36. 36.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  37. 37.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  38. 38.If a + b = 17 and ab = 70, what is a² + b²?
  39. 39.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 36².

Answer key

  1. 256
  2. 1591
  3. 6336
  4. 196
  5. 6241
  6. 196
  7. 10816
  8. 4
  9. 11025
  10. 45
  11. 5329
  12. 9216
  13. 157
  14. 3721
  15. 3564
  16. 5145
  17. 875
  18. 187
  19. 5625
  20. 1369
  21. 1596
  22. 4836
  23. 2491
  24. 4161
  25. 8091
  26. 2419
  27. 9
  28. 2436
  29. 7056
  30. 3969
  31. 90
  32. 6364
  33. 1849
  34. 3969
  35. 6396
  36. 2475
  37. 4
  38. 149
  39. 2484
  40. 1296

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