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Yeah I messed up a little, I think I copied the wrong set of numbers for the wrong problem or something.

I guess these were harder than they looked!

I just edited my posts a little. Sorry to messy up your thread. 

Puzzles from Reinout-g     (first posted 15/5/14)
 

Puzzle time! 

Here is 2 number puzzle for you.  

You do not have to use every number but you cannot use any number twice.

You can only use + - x and divide and brackets.

(1)       2,8,25,50,75,100  Magic number is 431   (This one is very hard)

(2)       4,6,25,50,75,100   Magic number is 821   (This one is easier but maybe not super easy  )

Wed 6/8/14

How to remember pemdas. 

@@ End of Day Wrap :       Tues 5/8/14      Sydney, Australia     Time 12:15 am  (Wednesday really)    ♬

Hi all,                                                                                         ♫♪ ♪ ♫ 

Still quiet but there were some good answers from NinjaDevo, Alan, AzizHusain, DragonSlayer, CPhill and Stu.  Thank you all.                              ♬  

Now for the posts:        

(1) What is a Venn diagram                 ♬  

Have a look at Ninja's code here

Dragon Slayer 

When you are doing questions like this you cannot just say x=1 or x=2.

It doesn't work quite that way  

I might try and find you some questions that you can answer legitimately and maybe learn something too.

Would you like that?

I didn't think that you were making them up Nataszaa.  But I think the book presents them in 'math speak' and when you interprete them into 'keyboard presentation' it is sometimes difficult to get the brackets etc in the correct places.

The book would not have presented it like this

#57 (3x 2/3)^7-6

Something is missing.  

I did give you 3 interpretations to choose from but you didn't say which was the correct one.  

Zegroes, if can't take a little honest criticism you will have difficulty in getting through life.

And Rosala - don't you say a thing!  

DragonSlayer, i tried it and no problem occured with me , it was all PERFECT!

i think the problem might be in the device your using or in your internet!anyways , im sure its just for sometime!

dont worry , it wont occur anymore!

You can write the 4th root of x either of these ways

$$\\\sqrt[4]{x}\qquad or \qquad x^{1/4}$$

It happened because you did not put \\ after \end{array}

I've done it accidentally before too but I've never experimented to see how it can be useful.

Soon I will be learning off you - I am already starting too!  

oh okaaayyy!

btw 15x3 , how did u get this name for xvxvx!any idea!or reason!

No that is because the problems has already been fixed.  

Somehow xvxvxv  who I call 15x3 managed to post a thread without a title and it was difficult to open.

Melody,.............i dont have an idea what u are talking about!im just.......................clueless!

Hi Ninja,

Somehow I think your first solution needs some brackets?  No it still won't work.  Plus you need to swap the 4 for 8/2    

Why don't you try the easier one?  The hard one is REALLY difficult.

(2)       4,6,25,50,75,100   Magic number is 821

Couldn't solve...

(1)       2,8,25,50,75,100  Magic number is 431

Couldn't solve...

Hey Melody,

I actually didn't mean for the boxed numbers to be on the side like they did, it actually came by accident. Lol!

Maybe you can explain why this happened. I basically just ended the array, then put in the box command and it appeared on the side like so. I was hoping to box the not equal sign that's already centered, but when I tried to box it, it just kept spooling and didn't give me a result in the output box.

The highlighted is what I was trying to box:

Here's my code:

\begin{array}{rll}

4x+5&=&4x-1\\

4(4)+5&=&4(4)-1\\

16+5&=&16-1\\

21&\neq&15

\end{array}

\boxed{21&\neq&15}\\

\begin{array}{rll}

4x+5&=&4x-1\\

4(15)+5&=&4(15)-1\\

60+5&=&60-1\\

65&\neq&59

\end{array}

\boxed{65\neq59}

Any help is appreciated. :)

Great. Will have a look on the transport home for this. Seems ok. Didnt know that would be the way to solve for d though. 

I don't know so you'l probably have to watch this instead. http://m.youtube.com/watch?v=yQ6utTt1TcE 

Yes okay, thanks Alan.  

What I'm really trying to do in the denominator is to find the x-axis distance between two limits. If I integrate a constant (k, say) with respect to x, I just get kx, which, if my limits are hi and lo gives me k(hi - lo).  If I set k to 1 then I just get hi - lo, the distance between the two limits.  (In the case of $$$\int dx$$$ the 1 is implicit).

Perhaps better to ignore some of the calculus and just think in terms of  average x distance = area.  The area can be found using calculus, and the distance using common sense! 

Yes but did what I said make sense?  

Actually if you'd presented the integral without anything there I would have been even more confused.  I didn't  know you could have an integral with nothing there.

Melody,

$$$\int1dx$ is really just $\int dx$\\\\
Had I done this in LaTeX I would probably just have written $\int dx$, but I did it using Mathcad, which requires an argument to be specified.$$

$$$\int_{lo}^{hi}dx$ is just the distance along the x-axis from x=lo to x=hi.$$

I think you've got it!