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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 227 · 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 16².
  2. 2.If a + b = 4 and ab = 3, what is a² + b²?
  3. 3.Use a² − b² = (a + b)(a − b) to find 61² − 35².
  4. 4.If a + b = 9 and ab = 18, what is a² + b²?
  5. 5.Find the value of x² − 2xy + y² when x = 15 and y = 8.
  6. 6.Use a² − b² = (a + b)(a − b) to find 88² − 27².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 23².
  8. 8.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  9. 9.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  10. 10.If a − b = 1 and ab = 30, what is a² + b²?
  11. 11.Find the value of x² − y² when x = 8 and y = 1.
  12. 12.Find the value of x² − y² when x = 13 and y = 7.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 73².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 28².
  15. 15.If a + b = 17 and ab = 60, what is a² + b²?
  16. 16.Use a² − b² = (a + b)(a − b) to find 72² − 42².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 98².
  18. 18.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 31².
  20. 20.Find the value of x² − y² when x = 4 and y = 2.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 84².
  22. 22.If a − b = 6 and ab = 55, what is a² + b²?
  23. 23.Use a² − b² = (a + b)(a − b) to find 26² − 6².
  24. 24.If a + b = 14 and ab = 45, what is a² + b²?
  25. 25.Find the value of x² + 2xy + y² when x = 15 and y = 1.
  26. 26.If a − b = 2 and ab = 15, what is a² + b²?
  27. 27.If a + b = 12 and ab = 32, what is a² + b²?
  28. 28.Use (a + b)² = a² + 2ab + b² to find 13².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 37².
  30. 30.Use a² − b² = (a + b)(a − b) to find 74² − 34².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 37².
  32. 32.Find the value of x² + 2xy + y² when x = 12 and y = 1.
  33. 33.If a − b = 1 and ab = 2, what is a² + b²?
  34. 34.Use (a − b)² = a² − 2ab + b² to find 77².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 17².
  36. 36.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  37. 37.Find the value of x² − y² when x = 13 and y = 5.
  38. 38.Use a² − b² = (a + b)(a − b) to find 37² − 31².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 64².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 46².

Answer key

  1. 256
  2. 10
  3. 2496
  4. 45
  5. 49
  6. 7015
  7. 529
  8. 399
  9. 391
  10. 61
  11. 63
  12. 120
  13. 5329
  14. 784
  15. 169
  16. 3420
  17. 9604
  18. 884
  19. 961
  20. 12
  21. 7056
  22. 146
  23. 640
  24. 106
  25. 256
  26. 34
  27. 80
  28. 169
  29. 1369
  30. 4320
  31. 1369
  32. 169
  33. 5
  34. 5929
  35. 289
  36. 25
  37. 144
  38. 408
  39. 4096
  40. 2116

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