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Two Plus Two Equals Five (Posted on 2022-11-29) Difficulty: 1 of 5
Provide two distinct fallacy methods thereby "proving" the undernoted false equality:
               2 + 2 = 5

See The Solution Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

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and another | Comment 3 of 4 |
  • Assume that we have two variables a and b, and that: a = b
  • Multiply both sides by a to get: a2 = ab
  • Subtract b2 from both sides: a2 - b2 = ab - b2
  • Then: (a + b)(a - b) = ab - b2
  • So that:  (a + b)(a - b) = b (a - b)
  • Factor out (a - b) from each side: a + b = b
  • Substitute b in for a to get: b + b = b
  • Add  3 b to each side: 5 b = 4 b 
  • Thus: 5 b = 2b + 2b
  • Divide by b: 5 = 2 + 2
  •  QED

Edited on November 29, 2022, 8:37 pm
  Posted by Steven Lord on 2022-11-29 20:34:53

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