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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 687 · 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 = 14 and y = 1.
  2. 2.If a + b = 3 and ab = 2, what is a² + b²?
  3. 3.Use (a − b)² = a² − 2ab + b² to find 91².
  4. 4.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  5. 5.Use a² − b² = (a + b)(a − b) to find 35² − 12².
  6. 6.Use a² − b² = (a + b)(a − b) to find 97² − 62².
  7. 7.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  8. 8.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 67².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 106².
  11. 11.If a − b = 2 and ab = 3, what is a² + b²?
  12. 12.Use (a + b)² = a² + 2ab + b² to find 43².
  13. 13.If a − b = 6 and ab = 16, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  15. 15.Use a² − b² = (a + b)(a − b) to find 24² − 4².
  16. 16.If a − b = 1 and ab = 2, what is a² + b²?
  17. 17.If a + b = 14 and ab = 40, what is a² + b²?
  18. 18.Find the value of x² − 2xy + y² when x = 15 and y = 12.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 17².
  20. 20.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  21. 21.If a − b = 3 and ab = 54, what is a² + b²?
  22. 22.Use (a + b)² = a² + 2ab + b² to find 57².
  23. 23.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 85².
  25. 25.Find the value of x² − y² when x = 6 and y = 3.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 84².
  27. 27.Find the value of x² + 2xy + y² when x = 7 and y = 2.
  28. 28.If a − b = 3 and ab = 10, what is a² + b²?
  29. 29.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 97².
  31. 31.Use a² − b² = (a + b)(a − b) to find 47² − 27².
  32. 32.Find the value of x² − y² when x = 12 and y = 9.
  33. 33.If a + b = 8 and ab = 7, what is a² + b²?
  34. 34.Use a² − b² = (a + b)(a − b) to find 93² − 63².
  35. 35.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  36. 36.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  37. 37.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  38. 38.If a + b = 13 and ab = 30, what is a² + b²?
  39. 39.Use (a + b)² = a² + 2ab + b² to find 51².
  40. 40.If a + b = 8 and ab = 15, what is a² + b²?

Answer key

  1. 169
  2. 5
  3. 8281
  4. 4
  5. 1081
  6. 5565
  7. 6336
  8. 399
  9. 4489
  10. 11236
  11. 10
  12. 1849
  13. 68
  14. 1591
  15. 560
  16. 5
  17. 116
  18. 9
  19. 289
  20. 4896
  21. 117
  22. 3249
  23. 3591
  24. 7225
  25. 27
  26. 7056
  27. 81
  28. 29
  29. 851
  30. 9409
  31. 1480
  32. 63
  33. 50
  34. 4680
  35. 9964
  36. 36
  37. 4
  38. 109
  39. 2601
  40. 34

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