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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 250 · 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 89².
  2. 2.If a − b = 3 and ab = 10, what is a² + b²?
  3. 3.Use (a + b)² = a² + 2ab + b² to find 41².
  4. 4.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  5. 5.Use a² − b² = (a + b)(a − b) to find 62² − 60².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 24².
  7. 7.If a + b = 8 and ab = 12, what is a² + b²?
  8. 8.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  9. 9.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 56².
  11. 11.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  12. 12.If a + b = 8 and ab = 15, what is a² + b²?
  13. 13.Find the value of x² + 2xy + y² when x = 15 and y = 6.
  14. 14.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  15. 15.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  16. 16.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  17. 17.Use a² − b² = (a + b)(a − b) to find 47² − 9².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 87².
  19. 19.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  20. 20.Use a² − b² = (a + b)(a − b) to find 46² − 13².
  21. 21.Use a² − b² = (a + b)(a − b) to find 77² − 58².
  22. 22.If a + b = 12 and ab = 11, what is a² + b²?
  23. 23.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  24. 24.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  25. 25.Find the value of x² − y² when x = 4 and y = 1.
  26. 26.If a − b = 3 and ab = 108, what is a² + b²?
  27. 27.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 82².
  29. 29.If a − b = 3 and ab = 54, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 58² − 10².
  31. 31.Find the value of x² + 2xy + y² when x = 7 and y = 2.
  32. 32.If a + b = 3 and ab = 2, what is a² + b²?
  33. 33.Use (a − b)² = a² − 2ab + b² to find 97².
  34. 34.If a − b = 4 and ab = 5, what is a² + b²?
  35. 35.Use a² − b² = (a + b)(a − b) to find 93² − 56².
  36. 36.Use a² − b² = (a + b)(a − b) to find 24² − 16².
  37. 37.If a + b = 13 and ab = 22, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 48².
  39. 39.If a − b = 3 and ab = 88, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 25² − 6².

Answer key

  1. 7921
  2. 29
  3. 1681
  4. 891
  5. 244
  6. 576
  7. 40
  8. 3536
  9. 1591
  10. 3136
  11. 384
  12. 34
  13. 441
  14. 6336
  15. 1584
  16. 9964
  17. 2128
  18. 7569
  19. 375
  20. 1947
  21. 2565
  22. 122
  23. 8051
  24. 25
  25. 15
  26. 225
  27. 4875
  28. 6724
  29. 117
  30. 3264
  31. 81
  32. 5
  33. 9409
  34. 26
  35. 5513
  36. 320
  37. 125
  38. 2304
  39. 185
  40. 589

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