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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 52 · 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)² = a² − 2ab + b² to find 41².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 55².
  3. 3.Find the value of x² − y² when x = 14 and y = 8.
  4. 4.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 96².
  6. 6.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  7. 7.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 71².
  9. 9.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  10. 10.Use a² − b² = (a + b)(a − b) to find 87² − 61².
  11. 11.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 79².
  13. 13.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 61².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 66².
  16. 16.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  17. 17.Find the value of x² − 2xy + y² when x = 15 and y = 12.
  18. 18.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  19. 19.Use a² − b² = (a + b)(a − b) to find 98² − 54².
  20. 20.Use (a + b)(a − b) = a² − b² to find 85 × 75.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 37².
  22. 22.If a − b = 1 and ab = 90, what is a² + b²?
  23. 23.Find the value of x² − 2xy + y² when x = 10 and y = 7.
  24. 24.Use a² − b² = (a + b)(a − b) to find 41² − 6².
  25. 25.Use a² − b² = (a + b)(a − b) to find 80² − 56².
  26. 26.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  27. 27.Find the value of x² − y² when x = 5 and y = 2.
  28. 28.Find the value of x² + 2xy + y² when x = 13 and y = 11.
  29. 29.If a + b = 12 and ab = 32, what is a² + b²?
  30. 30.Use (a + b)² = a² + 2ab + b² to find 45².
  31. 31.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  32. 32.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 98².
  34. 34.If a − b = 3 and ab = 4, what is a² + b²?
  35. 35.Use a² − b² = (a + b)(a − b) to find 48² − 43².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 78².
  37. 37.Use a² − b² = (a + b)(a − b) to find 78² − 13².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 27².
  39. 39.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  40. 40.Use a² − b² = (a + b)(a − b) to find 37² − 32².

Answer key

  1. 1681
  2. 3025
  3. 132
  4. 891
  5. 9216
  6. 3599
  7. 8019
  8. 5041
  9. 81
  10. 3848
  11. 9999
  12. 6241
  13. 1536
  14. 3721
  15. 4356
  16. 8084
  17. 9
  18. 384
  19. 6688
  20. 6375
  21. 1369
  22. 181
  23. 9
  24. 1645
  25. 3264
  26. 3575
  27. 21
  28. 576
  29. 80
  30. 2025
  31. 4836
  32. 836
  33. 9604
  34. 17
  35. 455
  36. 6084
  37. 5915
  38. 729
  39. 8096
  40. 345

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