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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 608 · 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 = 5 and y = 3.
  2. 2.Use a² − b² = (a + b)(a − b) to find 46² − 1².
  3. 3.If a − b = 1 and ab = 42, what is a² + b²?
  4. 4.Use (a − b)² = a² − 2ab + b² to find 13².
  5. 5.Find the value of x² − y² when x = 8 and y = 7.
  6. 6.If a + b = 5 and ab = 6, what is a² + b²?
  7. 7.Use a² − b² = (a + b)(a − b) to find 71² − 6².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 89².
  9. 9.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  10. 10.If a + b = 7 and ab = 10, what is a² + b²?
  11. 11.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  12. 12.Use a² − b² = (a + b)(a − b) to find 88² − 59².
  13. 13.Find the value of x² + 2xy + y² when x = 10 and y = 8.
  14. 14.Find the value of x² − y² when x = 11 and y = 4.
  15. 15.Use a² − b² = (a + b)(a − b) to find 44² − 6².
  16. 16.Find the value of x² + 2xy + y² when x = 10 and y = 3.
  17. 17.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  18. 18.Find the value of x² − y² when x = 3 and y = 1.
  19. 19.If a + b = 16 and ab = 63, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 48².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 94².
  22. 22.If a + b = 11 and ab = 10, what is a² + b²?
  23. 23.Use a² − b² = (a + b)(a − b) to find 38² − 4².
  24. 24.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 92².
  26. 26.Find the value of x² + 2xy + y² when x = 11 and y = 4.
  27. 27.Use a² − b² = (a + b)(a − b) to find 29² − 12².
  28. 28.Find the value of x² − y² when x = 10 and y = 1.
  29. 29.If a + b = 19 and ab = 84, what is a² + b²?
  30. 30.Use (a + b)² = a² + 2ab + b² to find 45².
  31. 31.Find the value of x² − 2xy + y² when x = 7 and y = 1.
  32. 32.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  33. 33.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  34. 34.If a + b = 15 and ab = 44, what is a² + b²?
  35. 35.Find the value of x² + 2xy + y² when x = 8 and y = 2.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 28².
  37. 37.Find the value of x² − 2xy + y² when x = 7 and y = 5.
  38. 38.Use a² − b² = (a + b)(a − b) to find 32² − 19².
  39. 39.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  40. 40.If a − b = 4 and ab = 45, what is a² + b²?

Answer key

  1. 4
  2. 2115
  3. 85
  4. 169
  5. 15
  6. 13
  7. 5005
  8. 7921
  9. 1599
  10. 29
  11. 25
  12. 4263
  13. 324
  14. 105
  15. 1900
  16. 169
  17. 4896
  18. 8
  19. 130
  20. 2304
  21. 8836
  22. 101
  23. 1428
  24. 9
  25. 8464
  26. 225
  27. 697
  28. 99
  29. 193
  30. 2025
  31. 36
  32. 3591
  33. 49
  34. 137
  35. 100
  36. 784
  37. 4
  38. 663
  39. 4
  40. 106

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