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Useless · 08-28-2008, 06:19 AM

Im glad im never taking Math ever again. This is the sorta thing that makes some people go postal.

Kogle · 08-28-2008, 12:24 PM

Teacher gave us the same problem in 9th grade Advanced Placement geometry, no one could figure it out. I'm now going to be a freshman in college and I'm taking Calculus 2 and I still don't know it! :[

Moshi2 · 08-28-2008, 02:05 PM

Quote:

Originally Posted by Xynh

Well, its back to school, and the first thing I learn from my math teacher is that 2 equals 1. He told the whole class to stop his proof if anyone can find a mathematical error. Well, no one did. Here's what he did:

Let A = B.
Multply both sides by A.
Now its: A^2 = AB.
Subtrace both sides by B^2.
Now its: A^2 - B^2 = AB - B^2.
When you factor it, it becomes: (A + B ) (A - B ) = B (A - B ).
Simplify it, making it: A + B = B.
Now, since A = B, you can make it: B + B = B.
Now to simplify: 2B/B = B/B.
Anything divided by itself is one, so the final equation would be: 2 = 1.

I cannot find an error in this equation, so.. What the hell?

There's the error in bold. To simplify (A+ B )(A-B ) = B(A- B ), what did you do? dividing both sides by (A- B ), right? BUT, A-B = 0 (based on your assumption A= B ) [division by zero]

Phr0zen · 08-28-2008, 02:46 PM

Quote:

Originally Posted by Moshi2

There's the error in bold. To simplify (A+ B )(A-B ) = B(A- B ), what did you do? dividing both sides by (A- B ), right? BUT, A-B = 0 (based on your assumption A= B ) [division by zero]

Yup. Division by zero. here is the same equation (x=y instead) and the solution from a math site:

Here’s our “proof”

1. Let x = y
2. so
x2 = xy
3. adding x2 to both sides of the equation we get
x2 + x2 = x2 + xy
4. simplifying we get
2 x2 = x2 + xy
5. subtract 2xy from both sides and we get
2 x2– 2xy = x2 + xy – 2xy
6. simplifying we get
2 x2– 2xy = x2– xy
7. factoring for (x2– xy) we get
2 (x2– xy) = 1 (x2– xy)
8. divide both sides by (x2– xy) we get
2 = 1

The problem with our proof is in step 8:

8. divide both sides by (x2– xy) we get
2 = 1

Answer:
In step 1 we said that x = y so (x2– xy) = 0 and you can’t divide by 0.

Our flawed proof is a good example of why dividing by 0 is not allowed. It’s not just because your math teacher told you so. It is because dividing by 0 can produce impossible results.

Pan · 08-28-2008, 04:58 PM

Quote:

Originally Posted by Xynh

Simplify it, making it: A + B = B.

That's not possible unless A=0. And if A=0 then B=0 and then you have to divide by zero so this equation is ****ed.

power_gamer_6 · 08-28-2008, 05:00 PM

He already figured it out last night when me and Manic helped him with it.

Quote:

I'm doing the equation on paper here, and I got to the factoring part:

(A+B)(A-B) = B (A-B) or, if you sub for numbers, (1+1)(1-1) = 1 (1-1)

And THAT is exactly where the problem lies.
The next step is to simplify, where it becomes:
A+B = B. That tells us B (A-B) should equal to B (B), which in turn just equals B.

If I'm correct, and you substitute for numbers, that should leave you with:
A+B = B, or, 1+1 = 0, because anything times zero is zero.
However, anything to the EXPONENT zero is 1.

Since this is not dealing with exponents anymore, and it's simple multiplication, I have come to the conclusion that the rest of the equation should not logically be possible to solve or proceed with as anything multiplied by zero is, as stated before, zero.

Our posts just got deleted by the update.

FabianN · 08-28-2008, 08:16 PM

Quote:

Originally Posted by zamwini

Your in for a fun time in math this year.

allright, I think i got it. You should be able to substitute letters with numbers, and still stay true. (I haven't taken math in 2 months, so I might be completely wrong.)
So, we are gonna subsititute A and B with 1, because they are equal.
1=1
then multiply, stays the same.
1=1
here, the entire problem falls apart. even if we were to continue and subtract B-
0=0
No way to simplify or do anything, so the problem is false.

Yup, he just summed it up.
That equation is akin to dividing by zero.
If you stick to variables, it works, but this is math, and in the end the variables represent real numbers, so you should be able to replace the letters with numbers, and work out that problem.

Thing is, you can't.

Try this equation agian and again, by using numbers instead of letters. Actually solve it, and you'll see that it is in fact impossible to solve, so no, your teacher is wrong. Either your teacher is wrong, or he was testing you and you all failed the test.

Ayabi · 08-28-2008, 08:33 PM

Quote:

Originally Posted by Useless

Im glad im never taking Math ever again. This is the sorta thing that makes some people go postal.

Indeed, just looking at these made me cringe.

illgamez · 08-28-2008, 09:19 PM

noooooo math online

Phr0zen · 08-28-2008, 09:39 PM

Quote:

Originally Posted by illgamez

noooooo math online

Math Online > WoW

muahahahhaha

08-28-2008, 06:19 AM	#11 (permalink)
Useless OnRPG Elite Member! Join Date: Jun 2006 Location: Ottawa, Canada Posts: 6,091 Reputation: 112	Im glad im never taking Math ever again. This is the sorta thing that makes some people go postal. __________________

08-28-2008, 09:19 PM	#19 (permalink)
illgamez Retired Staff Join Date: May 2006 Location: Where The Wild Things Are Posts: 3,391 Reputation: 51	noooooo math online __________________ MEMBER Since 2005 I'd rather be hated for who I am, than loved for who I am not.

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08-28-2008, 12:24 PM	#12 (permalink)
Kogle Luigi’s Pizza Join Date: Jun 2006 Posts: 131 Reputation: 12	Teacher gave us the same problem in 9th grade Advanced Placement geometry, no one could figure it out. I'm now going to be a freshman in college and I'm taking Calculus 2 and I still don't know it! :[