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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 760 · 40 sums
TalentJR

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 24².
  2. 2.Use a² − b² = (a + b)(a − b) to find 49² − 6².
  3. 3.Use a² − b² = (a + b)(a − b) to find 81² − 57².
  4. 4.If a + b = 12 and ab = 20, what is a² + b²?
  5. 5.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  6. 6.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  7. 7.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  8. 8.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  9. 9.Use a² − b² = (a + b)(a − b) to find 24² − 1².
  10. 10.If a − b = 10 and ab = 24, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 49² − 40².
  12. 12.If a + b = 3 and ab = 2, what is a² + b²?
  13. 13.Find the value of x² − 2xy + y² when x = 5 and y = 2.
  14. 14.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  15. 15.Use (a + b)² = a² + 2ab + b² to find 103².
  16. 16.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  17. 17.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  18. 18.Use a² − b² = (a + b)(a − b) to find 52² − 32².
  19. 19.Use a² − b² = (a + b)(a − b) to find 77² − 68².
  20. 20.Find the value of x² − y² when x = 13 and y = 5.
  21. 21.If a + b = 8 and ab = 15, what is a² + b²?
  22. 22.Use a² − b² = (a + b)(a − b) to find 50² − 15².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 14².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 64².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 31².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 25².
  27. 27.Find the value of x² − 2xy + y² when x = 12 and y = 10.
  28. 28.If a + b = 19 and ab = 90, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 29² − 24².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 32².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 19².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 16².
  33. 33.Use a² − b² = (a + b)(a − b) to find 79² − 66².
  34. 34.Find the value of x² + 2xy + y² when x = 10 and y = 3.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 47².
  36. 36.Find the value of x² + 2xy + y² when x = 10 and y = 8.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 44².
  38. 38.If a − b = 1 and ab = 110, what is a² + b²?
  39. 39.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  40. 40.Use a² − b² = (a + b)(a − b) to find 90² − 86².

Answer key

  1. 576
  2. 2365
  3. 3312
  4. 104
  5. 8096
  6. 3596
  7. 3584
  8. 81
  9. 575
  10. 148
  11. 801
  12. 5
  13. 9
  14. 4
  15. 10609
  16. 16
  17. 1519
  18. 1680
  19. 1305
  20. 144
  21. 34
  22. 2275
  23. 196
  24. 4096
  25. 961
  26. 625
  27. 4
  28. 181
  29. 265
  30. 1024
  31. 361
  32. 256
  33. 1885
  34. 169
  35. 2209
  36. 324
  37. 1936
  38. 221
  39. 169
  40. 704

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