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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 333 · 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 = 1.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 33².
  3. 3.Find the value of x² − 2xy + y² when x = 4 and y = 3.
  4. 4.Use a² − b² = (a + b)(a − b) to find 36² − 31².
  5. 5.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  6. 6.Use a² − b² = (a + b)(a − b) to find 89² − 76².
  7. 7.Use a² − b² = (a + b)(a − b) to find 26² − 20².
  8. 8.Use a² − b² = (a + b)(a − b) to find 91² − 81².
  9. 9.Use a² − b² = (a + b)(a − b) to find 80² − 28².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 78².
  11. 11.Use a² − b² = (a + b)(a − b) to find 36² − 33².
  12. 12.If a + b = 8 and ab = 7, what is a² + b²?
  13. 13.Use a² − b² = (a + b)(a − b) to find 31² − 28².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 12².
  15. 15.If a + b = 8 and ab = 12, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 12².
  17. 17.Find the value of x² − y² when x = 5 and y = 3.
  18. 18.Find the value of x² − 2xy + y² when x = 14 and y = 9.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 74².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 13².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 33².
  22. 22.If a − b = 4 and ab = 5, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 54².
  24. 24.If a + b = 13 and ab = 42, what is a² + b²?
  25. 25.If a − b = 4 and ab = 12, what is a² + b²?
  26. 26.If a − b = 2 and ab = 99, what is a² + b²?
  27. 27.Use a² − b² = (a + b)(a − b) to find 83² − 65².
  28. 28.If a + b = 15 and ab = 50, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 93² − 10².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 69².
  31. 31.Find the value of x² + 2xy + y² when x = 10 and y = 8.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 55².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 14².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 79².
  35. 35.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 35².
  37. 37.Find the value of x² − 2xy + y² when x = 9 and y = 6.
  38. 38.Use a² − b² = (a + b)(a − b) to find 72² − 63².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 27².
  40. 40.Use a² − b² = (a + b)(a − b) to find 33² − 8².

Answer key

  1. 81
  2. 1089
  3. 1
  4. 335
  5. 384
  6. 2145
  7. 276
  8. 1720
  9. 5616
  10. 6084
  11. 207
  12. 50
  13. 177
  14. 144
  15. 40
  16. 144
  17. 16
  18. 25
  19. 5476
  20. 169
  21. 1089
  22. 26
  23. 2916
  24. 85
  25. 40
  26. 202
  27. 2664
  28. 125
  29. 8549
  30. 4761
  31. 324
  32. 3025
  33. 196
  34. 6241
  35. 16
  36. 1225
  37. 9
  38. 1215
  39. 729
  40. 1025

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