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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 280 · 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 46².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 16².
  3. 3.Find the value of x² + 2xy + y² when x = 12 and y = 5.
  4. 4.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  5. 5.Find the value of x² − y² when x = 13 and y = 4.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 54².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 38².
  8. 8.Use a² − b² = (a + b)(a − b) to find 70² − 38².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 65².
  10. 10.Use a² − b² = (a + b)(a − b) to find 60² − 15².
  11. 11.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  12. 12.Use a² − b² = (a + b)(a − b) to find 27² − 6².
  13. 13.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 87².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 57².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 91².
  17. 17.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 21².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 79².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 11².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 78².
  22. 22.Use a² − b² = (a + b)(a − b) to find 37² − 23².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 19².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 101².
  25. 25.Use a² − b² = (a + b)(a − b) to find 29² − 1².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 69².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 47².
  28. 28.If a + b = 13 and ab = 40, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 37² − 15².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 24².
  31. 31.Find the value of x² + 2xy + y² when x = 15 and y = 13.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 97².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 44².
  34. 34.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  35. 35.If a + b = 9 and ab = 18, what is a² + b²?
  36. 36.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 32².
  38. 38.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  39. 39.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  40. 40.Find the value of x² − 2xy + y² when x = 11 and y = 9.

Answer key

  1. 2116
  2. 256
  3. 289
  4. 4851
  5. 153
  6. 2916
  7. 1444
  8. 3456
  9. 4225
  10. 3375
  11. 25
  12. 693
  13. 3575
  14. 7569
  15. 3249
  16. 8281
  17. 3584
  18. 441
  19. 6241
  20. 121
  21. 6084
  22. 840
  23. 361
  24. 10201
  25. 840
  26. 4761
  27. 2209
  28. 89
  29. 1144
  30. 576
  31. 784
  32. 9409
  33. 1936
  34. 9964
  35. 45
  36. 896
  37. 1024
  38. 1564
  39. 1
  40. 4

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