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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 507 · 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 = 14 and y = 8.
  2. 2.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  3. 3.If a + b = 5 and ab = 4, what is a² + b²?
  4. 4.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  5. 5.Find the value of x² − y² when x = 8 and y = 6.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 47².
  7. 7.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  8. 8.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 28².
  10. 10.If a + b = 21 and ab = 108, what is a² + b²?
  11. 11.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  12. 12.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  13. 13.Use a² − b² = (a + b)(a − b) to find 92² − 70².
  14. 14.If a + b = 13 and ab = 42, what is a² + b²?
  15. 15.Find the value of x² − 2xy + y² when x = 14 and y = 6.
  16. 16.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  17. 17.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  18. 18.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  19. 19.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  20. 20.Find the value of x² + 2xy + y² when x = 15 and y = 3.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 31².
  22. 22.If a + b = 17 and ab = 66, what is a² + b²?
  23. 23.Find the value of x² − 2xy + y² when x = 10 and y = 2.
  24. 24.Find the value of x² − y² when x = 13 and y = 10.
  25. 25.Find the value of x² + 2xy + y² when x = 13 and y = 12.
  26. 26.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  27. 27.Use a² − b² = (a + b)(a − b) to find 29² − 23².
  28. 28.Find the value of x² − 2xy + y² when x = 7 and y = 2.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 91².
  30. 30.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 75².
  32. 32.Find the value of x² − y² when x = 6 and y = 2.
  33. 33.If a + b = 6 and ab = 5, what is a² + b²?
  34. 34.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  35. 35.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  36. 36.If a − b = 3 and ab = 4, what is a² + b²?
  37. 37.Use a² − b² = (a + b)(a − b) to find 24² − 1².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 86².
  39. 39.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 46².

Answer key

  1. 36
  2. 9999
  3. 17
  4. 6396
  5. 28
  6. 2209
  7. 2499
  8. 3584
  9. 784
  10. 225
  11. 884
  12. 2464
  13. 3564
  14. 85
  15. 64
  16. 351
  17. 891
  18. 36
  19. 81
  20. 324
  21. 961
  22. 157
  23. 64
  24. 69
  25. 625
  26. 875
  27. 312
  28. 25
  29. 8281
  30. 4891
  31. 5625
  32. 32
  33. 26
  34. 3519
  35. 49
  36. 17
  37. 575
  38. 7396
  39. 2491
  40. 2116

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