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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 997 · 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 55².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 86².
  3. 3.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 29².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 33².
  6. 6.Find the value of x² − 2xy + y² when x = 11 and y = 8.
  7. 7.Use a² − b² = (a + b)(a − b) to find 55² − 43².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 48².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 57².
  10. 10.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  11. 11.If a + b = 3 and ab = 2, what is a² + b²?
  12. 12.If a − b = 1 and ab = 12, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 71².
  14. 14.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  15. 15.If a − b = 2 and ab = 15, what is a² + b²?
  16. 16.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  17. 17.Use a² − b² = (a + b)(a − b) to find 85² − 27².
  18. 18.Find the value of x² − 2xy + y² when x = 11 and y = 2.
  19. 19.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  20. 20.Use (a + b)² = a² + 2ab + b² to find 76².
  21. 21.If a − b = 1 and ab = 2, what is a² + b²?
  22. 22.Find the value of x² + 2xy + y² when x = 14 and y = 2.
  23. 23.Use (a − b)² = a² − 2ab + b² to find 62².
  24. 24.Use a² − b² = (a + b)(a − b) to find 38² − 13².
  25. 25.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  26. 26.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  27. 27.If a − b = 1 and ab = 20, what is a² + b²?
  28. 28.Use (a + b)² = a² + 2ab + b² to find 99².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 45².
  30. 30.Use a² − b² = (a + b)(a − b) to find 73² − 16².
  31. 31.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  32. 32.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  33. 33.Use a² − b² = (a + b)(a − b) to find 58² − 2².
  34. 34.If a + b = 15 and ab = 50, what is a² + b²?
  35. 35.If a − b = 9 and ab = 22, what is a² + b²?
  36. 36.If a − b = 2 and ab = 8, what is a² + b²?
  37. 37.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  38. 38.Find the value of x² − y² when x = 3 and y = 1.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 17².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 91².

Answer key

  1. 3025
  2. 7396
  3. 16
  4. 841
  5. 1089
  6. 9
  7. 1176
  8. 2304
  9. 3249
  10. 25
  11. 5
  12. 25
  13. 5041
  14. 3536
  15. 34
  16. 9964
  17. 6496
  18. 81
  19. 375
  20. 5776
  21. 5
  22. 256
  23. 3844
  24. 1275
  25. 4
  26. 2499
  27. 41
  28. 9801
  29. 2025
  30. 5073
  31. 2491
  32. 899
  33. 3360
  34. 125
  35. 125
  36. 20
  37. 396
  38. 8
  39. 289
  40. 8281

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