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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 475 · 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 − 2xy + y² when x = 10 and y = 8.
  2. 2.If a − b = 1 and ab = 30, what is a² + b²?
  3. 3.If a − b = 2 and ab = 80, what is a² + b²?
  4. 4.Use a² − b² = (a + b)(a − b) to find 63² − 5².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 84².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 32².
  7. 7.Find the value of x² + 2xy + y² when x = 9 and y = 7.
  8. 8.Use a² − b² = (a + b)(a − b) to find 91² − 25².
  9. 9.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 13².
  11. 11.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  12. 12.Find the value of x² − y² when x = 12 and y = 11.
  13. 13.Use a² − b² = (a + b)(a − b) to find 32² − 15².
  14. 14.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  15. 15.Find the value of x² − y² when x = 12 and y = 3.
  16. 16.If a + b = 9 and ab = 18, what is a² + b²?
  17. 17.If a − b = 7 and ab = 30, what is a² + b²?
  18. 18.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 39².
  20. 20.Find the value of x² + 2xy + y² when x = 13 and y = 3.
  21. 21.If a + b = 16 and ab = 63, what is a² + b²?
  22. 22.If a − b = 2 and ab = 3, what is a² + b²?
  23. 23.Use (a + b)² = a² + 2ab + b² to find 21².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 12².
  25. 25.Use a² − b² = (a + b)(a − b) to find 52² − 46².
  26. 26.If a − b = 1 and ab = 132, what is a² + b²?
  27. 27.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  28. 28.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 79².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 32².
  31. 31.If a + b = 4 and ab = 3, what is a² + b²?
  32. 32.Find the value of x² − 2xy + y² when x = 8 and y = 4.
  33. 33.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  34. 34.Use a² − b² = (a + b)(a − b) to find 73² − 29².
  35. 35.If a − b = 1 and ab = 72, what is a² + b²?
  36. 36.Use a² − b² = (a + b)(a − b) to find 27² − 9².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 41².
  38. 38.Find the value of x² − y² when x = 5 and y = 4.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 82².
  40. 40.Use (a + b)(a − b) = a² − b² to find 59 × 41.

Answer key

  1. 4
  2. 61
  3. 164
  4. 3944
  5. 7056
  6. 1024
  7. 256
  8. 7656
  9. 8091
  10. 169
  11. 169
  12. 23
  13. 799
  14. 384
  15. 135
  16. 45
  17. 109
  18. 16
  19. 1521
  20. 256
  21. 130
  22. 10
  23. 441
  24. 144
  25. 588
  26. 265
  27. 64
  28. 16
  29. 6241
  30. 1024
  31. 10
  32. 16
  33. 3591
  34. 4488
  35. 145
  36. 648
  37. 1681
  38. 9
  39. 6724
  40. 2419

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