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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 320 · 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 + 2xy + y² when x = 7 and y = 1.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 35².
  3. 3.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 78².
  5. 5.If a − b = 5 and ab = 84, what is a² + b²?
  6. 6.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  7. 7.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 84².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 92².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 79².
  11. 11.Find the value of x² − 2xy + y² when x = 9 and y = 2.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 44².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 61².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 25².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 35².
  16. 16.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  17. 17.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  18. 18.Use a² − b² = (a + b)(a − b) to find 72² − 10².
  19. 19.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  20. 20.Use (a + b)² = a² + 2ab + b² to find 19².
  21. 21.Use a² − b² = (a + b)(a − b) to find 74² − 33².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 94².
  23. 23.Use (a + b)(a − b) = a² − b² to find 108 × 92.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 48².
  25. 25.If a + b = 6 and ab = 8, what is a² + b²?
  26. 26.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  27. 27.Use a² − b² = (a + b)(a − b) to find 37² − 24².
  28. 28.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 32².
  30. 30.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 15².
  32. 32.If a − b = 8 and ab = 20, what is a² + b²?
  33. 33.If a + b = 18 and ab = 80, what is a² + b²?
  34. 34.Find the value of x² − 2xy + y² when x = 12 and y = 1.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 33².
  36. 36.If a − b = 3 and ab = 18, what is a² + b²?
  37. 37.Use (a − b)² = a² − 2ab + b² to find 18².
  38. 38.Use a² − b² = (a + b)(a − b) to find 21² − 3².
  39. 39.Use a² − b² = (a + b)(a − b) to find 41² − 38².
  40. 40.Use a² − b² = (a + b)(a − b) to find 65² − 63².

Answer key

  1. 64
  2. 1225
  3. 9
  4. 6084
  5. 193
  6. 3536
  7. 851
  8. 7056
  9. 8464
  10. 6241
  11. 49
  12. 1936
  13. 3721
  14. 625
  15. 1225
  16. 2496
  17. 2436
  18. 5084
  19. 2491
  20. 361
  21. 4387
  22. 8836
  23. 9936
  24. 2304
  25. 20
  26. 819
  27. 793
  28. 2475
  29. 1024
  30. 8091
  31. 225
  32. 104
  33. 164
  34. 121
  35. 1089
  36. 45
  37. 324
  38. 432
  39. 237
  40. 256

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