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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 325 · 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.Find the value of x² − y² when x = 14 and y = 2.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 76².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 12².
  4. 4.If a + b = 10 and ab = 24, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 93².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 18².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 97².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 34².
  9. 9.If a + b = 19 and ab = 88, what is a² + b²?
  10. 10.Use (a − b)² = a² − 2ab + b² to find 84².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 67².
  12. 12.If a − b = 3 and ab = 4, what is a² + b²?
  13. 13.If a + b = 7 and ab = 12, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 48².
  15. 15.Find the value of x² + 2xy + y² when x = 10 and y = 6.
  16. 16.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 95².
  18. 18.Use a² − b² = (a + b)(a − b) to find 66² − 58².
  19. 19.If a + b = 11 and ab = 28, what is a² + b²?
  20. 20.Find the value of x² − y² when x = 4 and y = 2.
  21. 21.Use a² − b² = (a + b)(a − b) to find 57² − 9².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 76².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 89².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 54².
  25. 25.If a − b = 2 and ab = 8, what is a² + b²?
  26. 26.If a − b = 2 and ab = 3, what is a² + b²?
  27. 27.Find the value of x² − y² when x = 7 and y = 1.
  28. 28.Use a² − b² = (a + b)(a − b) to find 66² − 34².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 82².
  30. 30.Find the value of x² − y² when x = 6 and y = 1.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 17².
  32. 32.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 13².
  34. 34.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  35. 35.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  36. 36.Use a² − b² = (a + b)(a − b) to find 62² − 3².
  37. 37.If a + b = 3 and ab = 2, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 29².
  39. 39.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 78².

Answer key

  1. 192
  2. 5776
  3. 144
  4. 52
  5. 8649
  6. 324
  7. 9409
  8. 1156
  9. 185
  10. 7056
  11. 4489
  12. 17
  13. 25
  14. 2304
  15. 256
  16. 364
  17. 9025
  18. 992
  19. 65
  20. 12
  21. 3168
  22. 5776
  23. 7921
  24. 2916
  25. 20
  26. 10
  27. 48
  28. 3200
  29. 6724
  30. 35
  31. 289
  32. 9996
  33. 169
  34. 2496
  35. 8084
  36. 3835
  37. 5
  38. 841
  39. 9991
  40. 6084

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