Jump to content
BrainDen.com - Brain Teasers
  • 0

comperr-like Impossible Math: The Elephant and The Mosquito


Question

Does the weight of an elephant equal the weight of the mosquito?

Let x be the weight of the elephant, y be the weight of the mosquito. Call the sum of the two weights 2v, then x+y=2v

From this equation we can obtain two more:

x - 2v = -y

and

x = -y + 2v

multiply:

x^2 - 2vx = y^2 - 2vy

add v^2:

x^2 - 2vx + v^2 = y^2 - 2vy + v^2

OR

(x-v)^2 = (y-v)^2

take square roots:

(x-v) = (y-v)

x = y

The elephant's weight equals the mosquitoes.

What is wrong here?

Link to post
Share on other sites

3 answers to this question

Recommended Posts

  • 0
(x-v)^2 = (y-v)^2

take square roots:

(x-v) = (y-v)

Mathematically when you take the square root of both sides you need a plus or minus on at leat one side:

(x-v) = ±(y-v)

The minus route gives you x + y = 2v again. Obviously you should choose to use the minus out of the plus or minus because anyone would assume they cannot be the same mass, yet you get back to your original equation and realize you are just wasting your time like I just realized.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Answer this question...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...