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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 210 · 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)(a − b) = a² − b² to find 56 × 44.
  2. 2.Find the value of x² + 2xy + y² when x = 13 and y = 2.
  3. 3.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  4. 4.If a − b = 1 and ab = 2, what is a² + b²?
  5. 5.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  6. 6.Use a² − b² = (a + b)(a − b) to find 43² − 8².
  7. 7.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 18².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 15².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 67².
  11. 11.Use a² − b² = (a + b)(a − b) to find 98² − 18².
  12. 12.Use a² − b² = (a + b)(a − b) to find 47² − 32².
  13. 13.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  14. 14.If a − b = 2 and ab = 35, what is a² + b²?
  15. 15.Use (a + b)² = a² + 2ab + b² to find 89².
  16. 16.Use a² − b² = (a + b)(a − b) to find 84² − 45².
  17. 17.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  18. 18.Use a² − b² = (a + b)(a − b) to find 81² − 17².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 52².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 26².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 38².
  22. 22.If a − b = 2 and ab = 24, what is a² + b²?
  23. 23.Use a² − b² = (a + b)(a − b) to find 77² − 39².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 35².
  25. 25.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  26. 26.If a + b = 8 and ab = 7, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 93².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 72².
  29. 29.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  30. 30.If a + b = 12 and ab = 20, what is a² + b²?
  31. 31.Use (a + b)² = a² + 2ab + b² to find 14².
  32. 32.If a − b = 1 and ab = 6, what is a² + b²?
  33. 33.Use a² − b² = (a + b)(a − b) to find 52² − 45².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 85².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 66².
  36. 36.Find the value of x² − 2xy + y² when x = 8 and y = 7.
  37. 37.Find the value of x² − 2xy + y² when x = 11 and y = 10.
  38. 38.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  39. 39.Find the value of x² − y² when x = 3 and y = 1.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 17².

Answer key

  1. 2464
  2. 225
  3. 2496
  4. 5
  5. 1519
  6. 1785
  7. 2491
  8. 324
  9. 225
  10. 4489
  11. 9280
  12. 1185
  13. 4
  14. 74
  15. 7921
  16. 5031
  17. 375
  18. 6272
  19. 2704
  20. 676
  21. 1444
  22. 52
  23. 4408
  24. 1225
  25. 1599
  26. 50
  27. 8649
  28. 5184
  29. 336
  30. 104
  31. 196
  32. 13
  33. 679
  34. 7225
  35. 4356
  36. 1
  37. 1
  38. 64
  39. 8
  40. 289

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