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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 185 · 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)(a − b) = a² − b² to find 79 × 61.
  2. 2.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  3. 3.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  4. 4.Use a² − b² = (a + b)(a − b) to find 44² − 14².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 98².
  6. 6.Find the value of x² − y² when x = 6 and y = 4.
  7. 7.If a − b = 3 and ab = 4, what is a² + b²?
  8. 8.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  9. 9.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  10. 10.Use a² − b² = (a + b)(a − b) to find 94² − 27².
  11. 11.Find the value of x² − y² when x = 4 and y = 2.
  12. 12.If a + b = 8 and ab = 7, what is a² + b²?
  13. 13.Find the value of x² − y² when x = 6 and y = 5.
  14. 14.Find the value of x² − 2xy + y² when x = 14 and y = 6.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 19².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 41².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 65².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 15².
  19. 19.Find the value of x² − y² when x = 5 and y = 4.
  20. 20.If a + b = 7 and ab = 10, what is a² + b²?
  21. 21.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 44².
  23. 23.Use a² − b² = (a + b)(a − b) to find 41² − 1².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 79².
  25. 25.Find the value of x² + 2xy + y² when x = 14 and y = 4.
  26. 26.Use a² − b² = (a + b)(a − b) to find 32² − 26².
  27. 27.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  28. 28.If a − b = 2 and ab = 3, what is a² + b²?
  29. 29.Find the value of x² + 2xy + y² when x = 12 and y = 11.
  30. 30.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 46².
  32. 32.Find the value of x² + 2xy + y² when x = 15 and y = 9.
  33. 33.Find the value of x² − y² when x = 7 and y = 3.
  34. 34.If a − b = 4 and ab = 5, what is a² + b²?
  35. 35.Find the value of x² + 2xy + y² when x = 10 and y = 6.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 52².
  37. 37.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  38. 38.Use a² − b² = (a + b)(a − b) to find 72² − 37².
  39. 39.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  40. 40.Find the value of x² + 2xy + y² when x = 13 and y = 7.

Answer key

  1. 4819
  2. 4891
  3. 6399
  4. 1740
  5. 9604
  6. 20
  7. 17
  8. 64
  9. 4
  10. 8107
  11. 12
  12. 50
  13. 11
  14. 64
  15. 361
  16. 1681
  17. 4225
  18. 225
  19. 9
  20. 29
  21. 6396
  22. 1936
  23. 1680
  24. 6241
  25. 324
  26. 348
  27. 4
  28. 10
  29. 529
  30. 9964
  31. 2116
  32. 576
  33. 40
  34. 26
  35. 256
  36. 2704
  37. 16
  38. 3815
  39. 3596
  40. 400

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