• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

2 + 2 = 5

#101
mactac said:
i will prove that 2 + 2 =5:

I dare you to find the mistake.

assume the variable a & the variable b.
assume that a=b

so, we get
a=b
a^2=ab (multiply both sides by a)
a^2 - b^2 = ab-b^2 (subtract b^2)
(a+b)(a-b)=b(a-b) (factor)
a+b=b (divide both sides by (a-b)
b+b=b (since a=b)
2b=b
2=1 (divide both sides by b)

since 2=1, and 5=2+2+1, we could also say that 5=1+2+1
which is equal to:
5=2+2

there you have it.


*NOTE**** if you have seen this before & know the "trick" don't tell... let some people squirm over it for a while
Click to expand...

(a+b)(a-b) doesn't equal a^2 - b^2, it equals a^2 + ab - b^2. :p

And really the whole argument of 0.9999 (repeating) not equaling 1 is that 0.3333 (repeating) x 3 approaches 1 but never reaches it. Go out far enough, though, and you'll get close enough that the difference is negligible.

(Correct me if I'm wrong -- I haven't done calc since 1985!)
 
#105
funkydjembe said:
Speaking of pi, there must be a "fraction" for pi. Or? Since the circumfrence is exactly 3.14 blah blah blah times the diameter? There is no infinity involved here. A circumfrence yay long and a diameter yay long. What is the "fraction" notation of pi? It must be there somewhere:eyebrow:
Click to expand...
The infinite part is the number of digits it takes to represent pi in base 10 (and in many other bases). While pi is an exact, and not especially large number, writing it exactly takes quite a while. If you write it as a fraction you will either be A: inexact (as in 22/7) or B: write a fraction with an infinite number of digits. That's why it's an irrational number.
 
#107
mactac said:
i will prove that 2 + 2 =5:

I dare you to find the mistake.

assume the variable a & the variable b.
assume that a=b

so, we get
a=b
a^2=ab (multiply both sides by a)
a^2 - b^2 = ab-b^2 (subtract b^2)
(a+b)(a-b)=b(a-b) (factor)
a+b=b (divide both sides by (a-b)
b+b=b (since a=b)
2b=b
2=1 (divide both sides by b)

since 2=1, and 5=2+2+1, we could also say that 5=1+2+1
which is equal to:
5=2+2

there you have it.


*NOTE**** if you have seen this before & know the "trick" don't tell... let some people squirm over it for a while
Click to expand...

Aargh! I am a math major at OU. Do you have any idea how hard it is not to scream at the screen for the glaring mistake?
 
#114
funkydjembe said:
If the value of "1" was as large as a trillion suns then "0.9--- would be an astronomical different number. 0.9---- tries to get closer but 1 stays the same distance away from 0.9----. Poor 0.9--- will never reach his dream of being 1.:(
Click to expand...

*sigh*

that wikipedia article about this issue is really good, especially about the misconceptions people have about the limiting process. my calc 2 prof often made a lot of asides, and one of them was about how we shouldn't view limits as taking place in time--the numbers are ALREADY there!
 
#115
somethingsin said:
I know another good 'proof':
...
(note: please don't try arguing against the method of proving by induction itself. It is a perfectly valid form of proof. Any flaws in this proof are in the specifics of this particular application of induction)
Click to expand...

induction proofs are fun and really beat the snot out of using the well-ordered principle. they really feel sketchy, though, so we like to make fun of'em. :D
 
#117
Brad, help! I have a classical mechanics mid term tomorrow!

I need to learn the following:

About Energy and Angular Momentum
About Central Conservative Forces
Rotating Frames
Potential Theory
Two Body Problem (Fairly easy)
Rigid Bodies
Many Body Systems

Yeah... this class was supposed to be a senior level class. They decided that sophmores had more use for it since it prepared you for E&M, Quantum, and the GRE's. They forgot to tone it down to our level, though. :(
 
#118
DubBeats CB said:
5x=0
3x+2x=0 (Factoring)
x(3+2)=0 (factor out an x)
3=-2

That always amused me........
Click to expand...

the problem with this is the first assumption is only true with values of x=0
ie the first assumption is a solve-able equation with only one possible value of x.

you cannot get a 0 on one side of an equation and start multiplying & dividing. i forget the name of the rule that says you cannot do this... anyone?
 
#120
Poop-Loops said:
I need to learn the following:

About Energy and Angular Momentum
About Central Conservative Forces
Rotating Frames
Potential Theory
Two Body Problem (Fairly easy)
Rigid Bodies
Many Body Systems

Yeah... this class was supposed to be a senior level class. They decided that sophmores had more use for it since it prepared you for E&M, Quantum, and the GRE's. They forgot to tone it down to our level, though. :(
Click to expand...
I don't want to judge since I don't know what the problems look like (they could be insane) but that is all the stuff I was doing in my first term at university. I'm just curious about what kind of depth you have to get into to make that a senior level course.

In any case, I feel for you - that's no fun :p
 

Latest posts

Top Bottom
Back