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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 424 · 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 36².
  2. 2.If a − b = 1 and ab = 6, what is a² + b²?
  3. 3.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 24².
  5. 5.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  6. 6.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 57².
  8. 8.If a − b = 1 and ab = 110, what is a² + b²?
  9. 9.If a − b = 3 and ab = 18, what is a² + b²?
  10. 10.Use a² − b² = (a + b)(a − b) to find 72² − 20².
  11. 11.Find the value of x² − y² when x = 6 and y = 3.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 18².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 87².
  14. 14.If a − b = 5 and ab = 66, what is a² + b²?
  15. 15.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  16. 16.Use a² − b² = (a + b)(a − b) to find 59² − 9².
  17. 17.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  18. 18.Use a² − b² = (a + b)(a − b) to find 94² − 37².
  19. 19.Use a² − b² = (a + b)(a − b) to find 29² − 9².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 44².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 52².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 67².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 104².
  24. 24.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  25. 25.If a + b = 16 and ab = 60, what is a² + b²?
  26. 26.If a + b = 4 and ab = 3, what is a² + b²?
  27. 27.Use (a − b)² = a² − 2ab + b² to find 86².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 14².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 47².
  30. 30.Find the value of x² − 2xy + y² when x = 6 and y = 4.
  31. 31.Find the value of x² + 2xy + y² when x = 8 and y = 5.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 29².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 45².
  34. 34.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 32².
  36. 36.Use a² − b² = (a + b)(a − b) to find 75² − 6².
  37. 37.If a − b = 1 and ab = 2, what is a² + b²?
  38. 38.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  39. 39.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  40. 40.Use a² − b² = (a + b)(a − b) to find 91² − 24².

Answer key

  1. 1296
  2. 13
  3. 25
  4. 576
  5. 9
  6. 875
  7. 3249
  8. 221
  9. 45
  10. 4784
  11. 27
  12. 324
  13. 7569
  14. 157
  15. 9996
  16. 3400
  17. 396
  18. 7467
  19. 760
  20. 1936
  21. 2704
  22. 4489
  23. 10816
  24. 4896
  25. 136
  26. 10
  27. 7396
  28. 196
  29. 2209
  30. 4
  31. 169
  32. 841
  33. 2025
  34. 8075
  35. 1024
  36. 5589
  37. 5
  38. 8091
  39. 6399
  40. 7705

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