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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 460 · 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 32 × 28.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 88².
  3. 3.Use a² − b² = (a + b)(a − b) to find 60² − 59².
  4. 4.Use a² − b² = (a + b)(a − b) to find 44² − 10².
  5. 5.Find the value of x² − y² when x = 12 and y = 2.
  6. 6.Find the value of x² − y² when x = 10 and y = 4.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 12².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 13².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 26².
  10. 10.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  11. 11.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 17².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 16².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 74².
  15. 15.Use a² − b² = (a + b)(a − b) to find 30² − 23².
  16. 16.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 91².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 88².
  19. 19.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  20. 20.Use a² − b² = (a + b)(a − b) to find 29² − 20².
  21. 21.If a − b = 1 and ab = 2, what is a² + b²?
  22. 22.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  23. 23.Find the value of x² − y² when x = 7 and y = 2.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 37².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 24².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 24².
  27. 27.If a + b = 6 and ab = 5, what is a² + b²?
  28. 28.If a + b = 4 and ab = 3, what is a² + b²?
  29. 29.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  30. 30.Use a² − b² = (a + b)(a − b) to find 94² − 10².
  31. 31.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  32. 32.If a − b = 2 and ab = 3, what is a² + b²?
  33. 33.Find the value of x² + 2xy + y² when x = 11 and y = 9.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 43².
  35. 35.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 32².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 89².
  38. 38.Use a² − b² = (a + b)(a − b) to find 43² − 8².
  39. 39.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 63².

Answer key

  1. 896
  2. 7744
  3. 119
  4. 1836
  5. 140
  6. 84
  7. 144
  8. 169
  9. 676
  10. 4896
  11. 375
  12. 289
  13. 256
  14. 5476
  15. 371
  16. 1584
  17. 8281
  18. 7744
  19. 16
  20. 441
  21. 5
  22. 81
  23. 45
  24. 1369
  25. 576
  26. 576
  27. 26
  28. 10
  29. 49
  30. 8736
  31. 4864
  32. 10
  33. 400
  34. 1849
  35. 319
  36. 1024
  37. 7921
  38. 1785
  39. 351
  40. 3969

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