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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 336 · 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 = 9 and y = 2.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 31².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 96².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 57².
  5. 5.Find the value of x² + 2xy + y² when x = 11 and y = 3.
  6. 6.If a + b = 3 and ab = 2, what is a² + b²?
  7. 7.Use (a + b)² = a² + 2ab + b² to find 37².
  8. 8.If a − b = 2 and ab = 99, what is a² + b²?
  9. 9.If a + b = 5 and ab = 4, what is a² + b²?
  10. 10.Use (a + b)² = a² + 2ab + b² to find 62².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 29².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 12².
  13. 13.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  14. 14.Use a² − b² = (a + b)(a − b) to find 97² − 63².
  15. 15.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  16. 16.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  17. 17.Use a² − b² = (a + b)(a − b) to find 21² − 9².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 15².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 36².
  20. 20.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  21. 21.Find the value of x² + 2xy + y² when x = 8 and y = 2.
  22. 22.Find the value of x² + 2xy + y² when x = 11 and y = 5.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 63².
  24. 24.If a + b = 5 and ab = 6, what is a² + b²?
  25. 25.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  26. 26.Find the value of x² − 2xy + y² when x = 4 and y = 3.
  27. 27.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  28. 28.Use a² − b² = (a + b)(a − b) to find 21² − 5².
  29. 29.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 92².
  31. 31.Use a² − b² = (a + b)(a − b) to find 90² − 16².
  32. 32.Use a² − b² = (a + b)(a − b) to find 23² − 11².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 87².
  34. 34.Use a² − b² = (a + b)(a − b) to find 63² − 5².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 79².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 26².
  37. 37.Find the value of x² + 2xy + y² when x = 10 and y = 7.
  38. 38.Use a² − b² = (a + b)(a − b) to find 37² − 5².
  39. 39.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 31².

Answer key

  1. 121
  2. 961
  3. 9216
  4. 3249
  5. 196
  6. 5
  7. 1369
  8. 202
  9. 17
  10. 3844
  11. 841
  12. 144
  13. 2464
  14. 5440
  15. 2491
  16. 2496
  17. 360
  18. 225
  19. 1296
  20. 25
  21. 100
  22. 256
  23. 3969
  24. 13
  25. 1
  26. 1
  27. 899
  28. 416
  29. 36
  30. 8464
  31. 7844
  32. 408
  33. 7569
  34. 3944
  35. 6241
  36. 676
  37. 289
  38. 1344
  39. 4896
  40. 961

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