I was doing some random math today and found a flaw in the mathematical concept of FOIL. I was curious if anybody knows of any more.

FOIL: http://pastebin.com/BhGeFTDm

Are there any more people can add?
technomonkey76 wrote:
FOIL: http://pastebin.com/BhGeFTDm

Are there any more people can add?

Code:
```    a = b                                   # Okay, so a equals b…     a^2 = ab                                # Makes sense… ...     (a+b)(a-b) = b(a-b)                     # Wait… ```
In this line, a-b = a-b = 0, so you get 0 = 0. No flaw.
KermMartian wrote:
technomonkey76 wrote:
FOIL: http://pastebin.com/BhGeFTDm

Are there any more people can add?

Code:
```    a = b                                   # Okay, so a equals b…     a^2 = ab                                # Makes sense… ...     (a+b)(a-b) = b(a-b)                     # Wait… ```
In this line, a-b = a-b = 0, so you get 0 = 0. No flaw.

True. Oh well. I tried too hard to see something wrong.
It took me a while to figure it out. Those kinds of things are often errors in stuff like a^2=4 -> a = 2 (where of course a = +/- 2).
Not to mention, you try to divide by 0 when you simplify that last line (# Wait...) to
Code:
`(a+b) = b`
because you divide by a-b which is a-a which is 0.
Ah, and that's probably the larger flaw that keeps the simplification from being correct all the way through. Nice catch there, tanner!
Thanks It took me a while to find it, but for these "flawed" math things, it usually is a divided by zero problem, so I just looked for that

Edit: Good job, of course, on your find. I wouldn't have thought it that far
KermMartian wrote:
Ah, and that's probably the larger flaw that keeps the simplification from being correct all the way through. Nice catch there, tanner!

Should I delete this topic, then?
No need. Just leave it to learn from.
technomonkey76 wrote:
I was doing some random math today and found a flaw in the mathematical concept of FOIL. I was curious if anybody knows of any more.

FOIL: http://pastebin.com/BhGeFTDm

Are there any more people can add?

You started with a=b and you later divided out (a-b) which is zero. That is NOT a flaw in foil. It is a math error on your part. Division by zero is not a mathematically defined operation.
Dingus, yes, I think we established that already. I think it would be interesting to go through some of the other commonly-cited examples of supposedly flawed math so we can find where the errors are.
Dingus wrote:
Division by zero is not a mathematically defined operation.

*Division by zero is not defined in real number arithmetic.
Yeah, I love little errors like that. It's like the .999 repeating == 1 thing.
.9 repeating is equal to 1, that's not an error.
merthsoft wrote:
.9 repeating is equal to 1, that's not an error.
^ Exactly this. In third grade or so (?) I actually debated with the teacher for about ten minutes about this before I was finally convinced. Here's another fallacies proof:

Code:
```    Step 1: -1/1 = 1/-1     Step 2: Taking the square root of both sides: sqrt(-1/1) = sqrt(1/-1)     Step 3: Simplifying: sqrt(-1) / sqrt(1) = sqrt(1) / sqrt(-1)     Step 4: In other words, i/1 = 1/i.     Step 5: Therefore, i / 2 = 1 / (2i),     Step 6: i/2 + 3/(2i) = 1/(2i) + 3/(2i),     Step 7: i (i/2 + 3/(2i) ) = i ( 1/(2i) + 3/(2i) ),     Step 8: (i^2)/2 + (3i)/2i = i/(2i) + (3i)/(2i),     Step 9: (-1)/2 + 3/2 = 1/2 + 3/2,     Step 10: and this shows that 1=2. ```

Register to Join the Conversation
Have your own thoughts to add to this or any other topic? Want to ask a question, offer a suggestion, share your own programs and projects, upload a file to the file archives, get help with calculator and computer programming, or simply chat with like-minded coders and tech and calculator enthusiasts via the site-wide AJAX SAX widget? Registration for a free Cemetech account only takes a minute.

»
» All times are UTC - 5 Hours

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum