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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 761 · 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 48².
  2. 2.Use a² − b² = (a + b)(a − b) to find 96² − 75².
  3. 3.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  4. 4.Use a² − b² = (a + b)(a − b) to find 30² − 28².
  5. 5.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  6. 6.Find the value of x² − y² when x = 10 and y = 4.
  7. 7.If a − b = 1 and ab = 110, what is a² + b²?
  8. 8.Use a² − b² = (a + b)(a − b) to find 69² − 49².
  9. 9.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  10. 10.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  11. 11.Use a² − b² = (a + b)(a − b) to find 33² − 30².
  12. 12.Find the value of x² + 2xy + y² when x = 13 and y = 12.
  13. 13.Find the value of x² − y² when x = 12 and y = 4.
  14. 14.If a + b = 18 and ab = 77, what is a² + b²?
  15. 15.Use (a + b)² = a² + 2ab + b² to find 92².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 69².
  17. 17.Use a² − b² = (a + b)(a − b) to find 62² − 42².
  18. 18.Use a² − b² = (a + b)(a − b) to find 95² − 89².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 25².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 14².
  21. 21.If a + b = 15 and ab = 50, what is a² + b²?
  22. 22.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  23. 23.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  24. 24.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  25. 25.Find the value of x² − y² when x = 15 and y = 8.
  26. 26.If a + b = 17 and ab = 66, what is a² + b²?
  27. 27.Find the value of x² − y² when x = 5 and y = 4.
  28. 28.Find the value of x² − 2xy + y² when x = 9 and y = 1.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 43².
  30. 30.Use a² − b² = (a + b)(a − b) to find 84² − 26².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 72².
  32. 32.Use a² − b² = (a + b)(a − b) to find 20² − 2².
  33. 33.If a + b = 7 and ab = 12, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 55².
  35. 35.Use a² − b² = (a + b)(a − b) to find 46² − 31².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 73².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 46².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 41².
  39. 39.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  40. 40.Use a² − b² = (a + b)(a − b) to find 40² − 32².

Answer key

  1. 2304
  2. 3591
  3. 3519
  4. 116
  5. 81
  6. 84
  7. 221
  8. 2360
  9. 319
  10. 1564
  11. 189
  12. 625
  13. 128
  14. 170
  15. 8464
  16. 4761
  17. 2080
  18. 1104
  19. 625
  20. 196
  21. 125
  22. 899
  23. 891
  24. 8051
  25. 161
  26. 157
  27. 9
  28. 64
  29. 1849
  30. 6380
  31. 5184
  32. 396
  33. 25
  34. 3025
  35. 1155
  36. 5329
  37. 2116
  38. 1681
  39. 351
  40. 576

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