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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 980 · 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 = 13 and y = 10.
  2. 2.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 65².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 37².
  5. 5.If a + b = 11 and ab = 18, what is a² + b²?
  6. 6.Use (a − b)² = a² − 2ab + b² to find 88².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 72².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 16².
  9. 9.Find the value of x² + 2xy + y² when x = 7 and y = 4.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 31².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 86².
  12. 12.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 55².
  14. 14.Use a² − b² = (a + b)(a − b) to find 66² − 39².
  15. 15.Find the value of x² − 2xy + y² when x = 13 and y = 3.
  16. 16.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 42².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 29².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 106².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 74².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 41².
  22. 22.If a + b = 4 and ab = 3, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 97².
  24. 24.If a − b = 7 and ab = 44, what is a² + b²?
  25. 25.Use (a + b)² = a² + 2ab + b² to find 36².
  26. 26.If a + b = 7 and ab = 10, what is a² + b²?
  27. 27.If a − b = 1 and ab = 6, what is a² + b²?
  28. 28.Use (a − b)² = a² − 2ab + b² to find 75².
  29. 29.Find the value of x² − y² when x = 7 and y = 1.
  30. 30.Find the value of x² − y² when x = 6 and y = 3.
  31. 31.If a + b = 19 and ab = 90, what is a² + b²?
  32. 32.Use (a − b)² = a² − 2ab + b² to find 74².
  33. 33.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 61².
  35. 35.Use a² − b² = (a + b)(a − b) to find 92² − 29².
  36. 36.Use a² − b² = (a + b)(a − b) to find 71² − 65².
  37. 37.Find the value of x² + 2xy + y² when x = 13 and y = 2.
  38. 38.If a − b = 3 and ab = 28, what is a² + b²?
  39. 39.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 103².

Answer key

  1. 9
  2. 4884
  3. 4225
  4. 1369
  5. 85
  6. 7744
  7. 5184
  8. 256
  9. 121
  10. 961
  11. 7396
  12. 9919
  13. 3025
  14. 2835
  15. 100
  16. 391
  17. 1764
  18. 841
  19. 11236
  20. 5476
  21. 1681
  22. 10
  23. 9409
  24. 137
  25. 1296
  26. 29
  27. 13
  28. 5625
  29. 48
  30. 27
  31. 181
  32. 5476
  33. 4899
  34. 3721
  35. 7623
  36. 816
  37. 225
  38. 65
  39. 6319
  40. 10609

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