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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 292 · 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 a² − b² = (a + b)(a − b) to find 99² − 67².
  2. 2.Find the value of x² − 2xy + y² when x = 8 and y = 1.
  3. 3.Find the value of x² − y² when x = 15 and y = 3.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 57².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 49².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 61².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 103².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 65².
  9. 9.Use a² − b² = (a + b)(a − b) to find 95² − 13².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 38².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 16².
  12. 12.Use a² − b² = (a + b)(a − b) to find 89² − 48².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 58².
  14. 14.Find the value of x² − 2xy + y² when x = 11 and y = 1.
  15. 15.If a + b = 6 and ab = 8, what is a² + b²?
  16. 16.If a − b = 2 and ab = 3, what is a² + b²?
  17. 17.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  18. 18.If a − b = 7 and ab = 8, what is a² + b²?
  19. 19.Use (a + b)² = a² + 2ab + b² to find 17².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 82².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 98².
  22. 22.Use a² − b² = (a + b)(a − b) to find 61² − 46².
  23. 23.Use a² − b² = (a + b)(a − b) to find 83² − 79².
  24. 24.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  25. 25.Find the value of x² − y² when x = 4 and y = 2.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 11².
  27. 27.Use a² − b² = (a + b)(a − b) to find 66² − 33².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 75².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 23².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 79².
  31. 31.Find the value of x² + 2xy + y² when x = 14 and y = 3.
  32. 32.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 34².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 24².
  35. 35.Use a² − b² = (a + b)(a − b) to find 77² − 13².
  36. 36.If a + b = 11 and ab = 18, what is a² + b²?
  37. 37.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  38. 38.Find the value of x² − 2xy + y² when x = 15 and y = 11.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 12².
  40. 40.If a + b = 19 and ab = 90, what is a² + b²?

Answer key

  1. 5312
  2. 49
  3. 216
  4. 3249
  5. 2401
  6. 3721
  7. 10609
  8. 4225
  9. 8856
  10. 1444
  11. 256
  12. 5617
  13. 3364
  14. 100
  15. 20
  16. 10
  17. 1591
  18. 65
  19. 289
  20. 6724
  21. 9604
  22. 1605
  23. 648
  24. 4899
  25. 12
  26. 121
  27. 3267
  28. 5625
  29. 529
  30. 6241
  31. 289
  32. 375
  33. 1156
  34. 576
  35. 5760
  36. 85
  37. 896
  38. 16
  39. 144
  40. 181

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