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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 477 · 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.Find the value of x² − y² when x = 7 and y = 1.
  2. 2.If a − b = 11 and ab = 12, what is a² + b²?
  3. 3.Find the value of x² − y² when x = 13 and y = 5.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 91².
  5. 5.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  6. 6.Find the value of x² − 2xy + y² when x = 8 and y = 1.
  7. 7.Find the value of x² − y² when x = 9 and y = 1.
  8. 8.Use a² − b² = (a + b)(a − b) to find 22² − 2².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 27².
  10. 10.Use a² − b² = (a + b)(a − b) to find 71² − 21².
  11. 11.Find the value of x² − y² when x = 7 and y = 5.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 94².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 26².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 86².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 79².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 65².
  17. 17.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  18. 18.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 57².
  20. 20.If a − b = 9 and ab = 36, what is a² + b²?
  21. 21.Use a² − b² = (a + b)(a − b) to find 32² − 8².
  22. 22.Use a² − b² = (a + b)(a − b) to find 61² − 37².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 94².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 21².
  25. 25.Use a² − b² = (a + b)(a − b) to find 20² − 19².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 93².
  27. 27.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  28. 28.Find the value of x² + 2xy + y² when x = 8 and y = 2.
  29. 29.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 89².
  31. 31.Find the value of x² + 2xy + y² when x = 6 and y = 2.
  32. 32.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  33. 33.If a − b = 1 and ab = 12, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 14².
  35. 35.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  36. 36.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  37. 37.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  38. 38.If a − b = 1 and ab = 72, what is a² + b²?
  39. 39.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  40. 40.If a + b = 4 and ab = 3, what is a² + b²?

Answer key

  1. 48
  2. 145
  3. 144
  4. 8281
  5. 81
  6. 49
  7. 80
  8. 480
  9. 729
  10. 4600
  11. 24
  12. 8836
  13. 676
  14. 7396
  15. 6241
  16. 4225
  17. 875
  18. 1599
  19. 3249
  20. 153
  21. 960
  22. 2352
  23. 8836
  24. 441
  25. 39
  26. 8649
  27. 2496
  28. 100
  29. 9999
  30. 7921
  31. 64
  32. 144
  33. 25
  34. 196
  35. 36
  36. 6319
  37. 375
  38. 145
  39. 25
  40. 10

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