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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 633 · 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.If a + b = 15 and ab = 36, what is a² + b²?
  2. 2.Use (a − b)² = a² − 2ab + b² to find 75².
  3. 3.Find the value of x² − y² when x = 10 and y = 1.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 35².
  5. 5.Find the value of x² + 2xy + y² when x = 14 and y = 13.
  6. 6.Use a² − b² = (a + b)(a − b) to find 98² − 43².
  7. 7.Use a² − b² = (a + b)(a − b) to find 88² − 17².
  8. 8.Find the value of x² − y² when x = 10 and y = 9.
  9. 9.If a + b = 6 and ab = 5, what is a² + b²?
  10. 10.Use a² − b² = (a + b)(a − b) to find 42² − 16².
  11. 11.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  12. 12.Find the value of x² + 2xy + y² when x = 13 and y = 11.
  13. 13.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  14. 14.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  15. 15.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 33².
  17. 17.Find the value of x² + 2xy + y² when x = 15 and y = 1.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 16².
  19. 19.Find the value of x² − y² when x = 5 and y = 3.
  20. 20.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 108².
  22. 22.Use a² − b² = (a + b)(a − b) to find 96² − 10².
  23. 23.If a − b = 5 and ab = 36, what is a² + b²?
  24. 24.Use a² − b² = (a + b)(a − b) to find 94² − 11².
  25. 25.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 37².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 15².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 35².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 34².
  30. 30.Use a² − b² = (a + b)(a − b) to find 93² − 55².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 82².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 53².
  33. 33.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  34. 34.If a − b = 2 and ab = 8, what is a² + b²?
  35. 35.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 61².
  37. 37.If a − b = 8 and ab = 20, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 82².
  39. 39.Use a² − b² = (a + b)(a − b) to find 29² − 9².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 28².

Answer key

  1. 153
  2. 5625
  3. 99
  4. 1225
  5. 729
  6. 7755
  7. 7455
  8. 19
  9. 26
  10. 1508
  11. 1519
  12. 576
  13. 8036
  14. 1599
  15. 4
  16. 1089
  17. 256
  18. 256
  19. 16
  20. 1596
  21. 11664
  22. 9116
  23. 97
  24. 8715
  25. 8075
  26. 1369
  27. 225
  28. 1225
  29. 1156
  30. 5624
  31. 6724
  32. 2809
  33. 884
  34. 20
  35. 4899
  36. 3721
  37. 104
  38. 6724
  39. 760
  40. 784

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