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## #1 Re: This is Cool » Einstein: "I never failed in mathematics" » 2011-07-31 04:57:31

I read a great book about Einstein that actually answered most of those questions from that website and showed me a side of him I had never known before. It is called "Einstein's Mistakes"

## #2 Re: Help Me ! » Probability Question » 2011-07-19 02:29:14

gAr:

The way I looked at the problem, I would stop looking once I hit a pair.

## #3 Help Me ! » Probability Question » 2011-07-15 16:00:34

MathPro101
Replies: 5

Hello all,

I am just passing time playing with a deck of cards and thought of a probability question. It is a very straight forward problem, but for some reason I cannot figure out the solution.

If I have a deck of 52 cards, shuffled, and I turn over one card at a time, what is the probability that I will see 2 of the same number in a row? (i.e., flipping over a 9, followed by another 9).

Let me know what you all think! Thank you.

## #4 Re: Jokes » Math Pick-up Lines » 2011-07-10 06:55:39

Oh I like the You-Substitution one. Very nice.

## #5 Re: This is Cool » Grandi's series (1-1+1-1...) » 2011-07-09 16:58:30

Question: When I explained Grandi's series to a friend, they stated that addition is commutative, which is true. They wanted to know why the commutative property is allowed to be violated for this series. I suggested that it has to do with the fact that it is a series, and not just any normal addition. Could anyone help me explain why we don't break any laws? Thank you.

## #6 Jokes » Math Pick-up Lines » 2011-07-09 16:47:00

MathPro101
Replies: 447

Just two math pickup lines I thought were pretty humorous.

"You and I add up better than a Reimman sum"
"My love for you is like dividing by 0; its so undefined"

## #7 Re: Help Me ! » Non-math related question » 2011-06-20 06:32:11

Gotcha, I have a lot of work to do

## #8 Re: Help Me ! » Non-math related question » 2011-06-20 05:49:03

WOOOO!!!! What's next?

## #9 Re: Help Me ! » Powers of 3 and integers » 2011-06-20 05:44:51

If this helps, I noticed that the red line, 3^0, appears in the first two, then not in the third, then the next two, but not the sixth...and so on..

## #10 Re: Help Me ! » Non-math related question » 2011-06-20 05:39:27

Hi gAr,

Thank you very much.

## #11 Help Me ! » Non-math related question » 2011-06-20 05:33:08

MathPro101
Replies: 6

Hey, just a quick question about the forum. What do I have to do to get rid of my "Novice" title? Thank you.

## #12 Re: Help Me ! » Understanding a Coordinate system » 2011-06-20 05:23:26

Are you referring to uv transformations in calculus?

## #13 Re: Help Me ! » swich equation to y=mx+b » 2011-06-19 11:35:40

Slope intercept form is the form y=mx+b.

This means that in each equation, we must solve for y in terms of x and a constant, b.

To solve for y, we need to have it alone on one side. In order to do that, we must move x to the other side. In all three equations, x is being added to y on the left side, so in order to move x over, we must subtract x from the left side. But whatever we do to the left side we must do to the right side. So after one step, you should have

x + 2y - x= -4 - x

x + y - x= 3 -x

x + 3y - x= -6 - x

which is the same as

2y= -4 - x

y= 3 -x

3y= -6 - x

Now, the second equation is in slope-intercept form, but the first and third are not. We must apply the same algebraic strategy that we did in the first step to get y alone. For example, in the first equation, y is being multiplied by 2. So in order to get rid of the two, we must divide the y by 2. But we must also divide the WHOLE right side by two, not just the -4. Once you do that for the first and third equation, you should end up with

y= -2 - x/2
y= 3 - x
y= -2 -x/3

Does that help?

## #14 Introductions » Hello » 2011-06-18 08:57:41

MathPro101
Replies: 2

Hi Everyone,

My name is David from Colorado. I am an undergraduate studying Applied Mathematics at an engineering school. I joined the forum to talk to people who love math as much as me. I look forward to chatting about math. Thanks!

## #15 Re: This is Cool » Complex Equation » 2011-06-18 05:54:56

Very Good! One quick addition to that would be to say that θ = π/2 ± 2πn, where n=0,1,2,.. This is the same as rotating on the unit circle and getting back to the same place each time. Therefore the true answer should be e^(-π/2 ± 2πn), which is still a real number!

There is another way of solving this problem that uses a different technique. Can anyone figure that one out? It simplifies things greatly.

## #16 Re: Help Me ! » Interesting question MIND FREAKING » 2011-06-09 05:49:43

When you set them all equal to each other, {A}^{1/A}={B}^{1/B}={C}^{1/C}, can you not conclude that A=B=C?

## #17 This is Cool » Complex Equation » 2011-06-09 04:47:27

MathPro101
Replies: 2

I found this video on youtube of an MIT Physics lecture. If you jump ahead to around 45 minutes, the professor offers a math problem that I found interesting.

It took me a long time to work through it, but if you know the trick, it can be solved in less than 10 seconds.

i^i, where i = sqrt(-1)

the clue is that i=e^i(pi/2 plusminus 2*pi*n), n=0,1,2,...

Have fun with it, let me know what you think.