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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 438 · 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 34 × 26.
  2. 2.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  3. 3.Use a² − b² = (a + b)(a − b) to find 48² − 2².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 34².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 47².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 29².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 59².
  8. 8.Find the value of x² + 2xy + y² when x = 10 and y = 1.
  9. 9.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  10. 10.Use a² − b² = (a + b)(a − b) to find 73² − 46².
  11. 11.Find the value of x² − y² when x = 14 and y = 10.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 101².
  13. 13.If a − b = 4 and ab = 21, what is a² + b²?
  14. 14.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  15. 15.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  16. 16.Find the value of x² − y² when x = 14 and y = 2.
  17. 17.If a + b = 3 and ab = 2, what is a² + b²?
  18. 18.If a − b = 1 and ab = 90, what is a² + b²?
  19. 19.Use (a + b)² = a² + 2ab + b² to find 93².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 72².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 51².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 47².
  23. 23.If a + b = 21 and ab = 110, what is a² + b²?
  24. 24.Use a² − b² = (a + b)(a − b) to find 55² − 25².
  25. 25.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  26. 26.Find the value of x² + 2xy + y² when x = 7 and y = 3.
  27. 27.If a − b = 9 and ab = 10, what is a² + b²?
  28. 28.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 69².
  30. 30.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  31. 31.If a + b = 9 and ab = 8, what is a² + b²?
  32. 32.If a + b = 18 and ab = 80, what is a² + b²?
  33. 33.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  34. 34.Use a² − b² = (a + b)(a − b) to find 64² − 19².
  35. 35.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 79².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 77².
  38. 38.If a − b = 2 and ab = 24, what is a² + b²?
  39. 39.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  40. 40.Use a² − b² = (a + b)(a − b) to find 72² − 59².

Answer key

  1. 884
  2. 9991
  3. 2300
  4. 1156
  5. 2209
  6. 841
  7. 3481
  8. 121
  9. 6364
  10. 3213
  11. 96
  12. 10201
  13. 58
  14. 1
  15. 1519
  16. 192
  17. 5
  18. 181
  19. 8649
  20. 5184
  21. 2601
  22. 2209
  23. 221
  24. 2400
  25. 899
  26. 100
  27. 101
  28. 875
  29. 4761
  30. 9984
  31. 65
  32. 164
  33. 396
  34. 3735
  35. 864
  36. 6241
  37. 5929
  38. 52
  39. 2419
  40. 1703

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