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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 204 · 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 97².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 41².
  3. 3.Use a² − b² = (a + b)(a − b) to find 96² − 8².
  4. 4.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  5. 5.Find the value of x² + 2xy + y² when x = 14 and y = 2.
  6. 6.Find the value of x² − 2xy + y² when x = 11 and y = 1.
  7. 7.If a + b = 7 and ab = 12, what is a² + b²?
  8. 8.Use (a + b)² = a² + 2ab + b² to find 102².
  9. 9.Use a² − b² = (a + b)(a − b) to find 20² − 5².
  10. 10.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  11. 11.If a − b = 2 and ab = 48, what is a² + b²?
  12. 12.Find the value of x² − 2xy + y² when x = 13 and y = 2.
  13. 13.Use a² − b² = (a + b)(a − b) to find 70² − 57².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 11².
  15. 15.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  16. 16.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  17. 17.Find the value of x² − 2xy + y² when x = 9 and y = 8.
  18. 18.Find the value of x² + 2xy + y² when x = 12 and y = 2.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 12².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 98².
  21. 21.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 29².
  23. 23.If a + b = 14 and ab = 40, what is a² + b²?
  24. 24.Use a² − b² = (a + b)(a − b) to find 27² − 13².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 43².
  26. 26.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  27. 27.If a + b = 9 and ab = 8, what is a² + b²?
  28. 28.Use (a − b)² = a² − 2ab + b² to find 18².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 68².
  30. 30.If a + b = 16 and ab = 48, what is a² + b²?
  31. 31.Use (a − b)² = a² − 2ab + b² to find 45².
  32. 32.Use a² − b² = (a + b)(a − b) to find 76² − 33².
  33. 33.Use a² − b² = (a + b)(a − b) to find 91² − 21².
  34. 34.If a − b = 3 and ab = 28, what is a² + b²?
  35. 35.Use (a + b)² = a² + 2ab + b² to find 81².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 13².
  37. 37.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 52².
  39. 39.Use a² − b² = (a + b)(a − b) to find 63² − 51².
  40. 40.Use (a + b)(a − b) = a² − b² to find 106 × 94.

Answer key

  1. 9409
  2. 1681
  3. 9152
  4. 2491
  5. 256
  6. 100
  7. 25
  8. 10404
  9. 375
  10. 81
  11. 100
  12. 121
  13. 1651
  14. 121
  15. 6384
  16. 3551
  17. 1
  18. 196
  19. 144
  20. 9604
  21. 1519
  22. 841
  23. 116
  24. 560
  25. 1849
  26. 6336
  27. 65
  28. 324
  29. 4624
  30. 160
  31. 2025
  32. 4687
  33. 7840
  34. 65
  35. 6561
  36. 169
  37. 2451
  38. 2704
  39. 1368
  40. 9964

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