Mathematics

anon

10:00 AM

I am sea turtles :)

Benja

which one

there's a shit ton

anon

how do I specify which one?

Benja

well there's a lot of people with that username

@anon I added you

Sush

@anon, how (x^(ab)-1)/(x-1) is divisible by (x^a-1)/(x-1)?

anon

when you divide the first by the second, you get an integer

Ashish Nitin Patil

10:06 AM

Hello everyone.

badass

hi

Ashish Nitin Patil

Just a small formatting question (I tried a few things but couldn't get it)

Sush

@anon, many many thanks sir, got everything clear.

Ashish Nitin Patil

How to represent 10C4 ?

anon

in LaTeX?

Ashish Nitin Patil

10:07 AM

I tried $10\choose4$

yes I suppose

Sush

$\binom{10}{4}$

Ashish Nitin Patil

Ok thanks @Sush

anon

${}_{10}C_4$ , although higher up we use $\binom{10}{4}$

${10\choose4}$ actually works just as well

Sush

A troop 5 meters long starts marching. A soldier at the end of the file steps out and starts marching forward at a higher speed. On reaching the head of the column, he immediately turns around and marches back at the same speed. As soon as he reaches the end of the file, the troop stops marching, and it is found that the troop has moved by exactly 5 meters. What distance has the soldier travelled?

Ashish Nitin Patil

Thanks @anon I am not using the curly braces properly

Sush

10:17 AM

@AshishNitinPatil, will you answer me please?

Ashish Nitin Patil

Sorry @Sush was busy for a bit

Looking into your question

Sush

@AshishNitinPatil, thnx.

Ashish Nitin Patil

Let's say the troop has a speed x metres per hour.

And let's say soldier moves with x+y speed.

Total Time taken = 5m/x (troops speed)

Gimme some time :P

usukidoll

Calc iv is making me sad

Ashish Nitin Patil

10:32 AM

I see

usukidoll

http://assets.openstudy.com/updates/attachments/52981fbbe4b04e12f8221eb3-usukidoll-1385715305230-scan1310240004.jpg
#14 is making me mad

Ashish Nitin Patil

the length is given :/

usukidoll

my lame attempt seen here
http://openstudy.com/study#/updates/52985c22e4b04e12f8222aa1

Sush

@AshishNitinPatil, don't we get a numeric answer?

Ashish Nitin Patil

@Sush Lets keep T & S for speeds of Troops & Soldier respectively

Thus, 5 x T is total time taken

Ethan

10:35 AM

what is happening

Ashish Nitin Patil

While going in same direction, soldier takes (T - S) x 5 time

While in the opposite direction (T + S) x 5

Thus, 5T = (T-S)*5 + (T+S)*5

I am sorry

5T = (S-T)*5 + (S+T)*5

I goofed it up again.

Sush

@AshishNitinPatil, Oh don't worry. if i ask this on main site without my any effort, will I get answer? What is your advice?

Ashish Nitin Patil

Ok answering in a bit

@Sush link to the question please

Sush

@AshishNitinPatil, pardon my ignorance. which link do you want?

TheNotMe

anyone good at automata / formal languages?

usukidoll

10:42 AM

I'm a fuzzball in calculus iv

Ashish Nitin Patil

@Sush Oh, you haven't actually asked, that's ok, give me a bit

of time

badass

@usukidoll have you tried the Khan Academy?

usukidoll

T_T I can't help it if my prof wants this assignment ASAP and his lectures are so slow and some other stuff just pops up I just...feel...overwhelmed

Karl Kronenfeld

@Sush I feel like there is a cute, nonalgebraic way to solve this.

Sush

@KarlKronenfeld, will you mention it for me please?

Ashish Nitin Patil

10:46 AM

I would love that too... currently I am messing up simple speed-distance-time arithmetic :/

Karl Kronenfeld

@Sush I don't see it yet.

Sush

Soooooo, what should I do? shall i ask it on main math.se without any effort?

Karl Kronenfeld

I'm just working on it for my own enjoyment. Do what ever you would like.

Ashish Nitin Patil

@Sush you should ask on the main site than relying on me.

Sush

@KarlKronenfeld, I am waiting. I think the answer should not be "information is lacking"

Ashish Nitin Patil

10:49 AM

I do think so @Sush

But, that's a maybe

Karl Kronenfeld

@Sush I think there is enough information, i.e. I could do it algebraically, I think. I just want to exploit a symmetry that I noticed to see if there is a nicer solution.

Ethan

iv?

Sush

@AshishNitinPatil, thanks. It is the question from "TEST OF MATHEMATICS AT 10+2 LEVEL" book and have tried for it a lot.

Ashish Nitin Patil

brb afk (Gotta go & check my exam paper)

usukidoll

I give up T_T

cries

badass

10:55 AM

nvm :(

usukidoll

I need a shoulder to cry on T_T

badass

don't you have shoulders?

usukidoll

Cries

Ethan

Where did all these new people come from

badass

Let the speed of the troop be x mps and the speed of the soldier be
y mps. Then, (5/x+y) + (5/x–y) = 5/y
OR 2x/(x^2 – y^2) = 1/y
OR x^2 – y^2 – 2xy = 0

OR x/y = (1 +- 2^1/2)/1 Since, distance is directly proportionate to speed. Hence when the troops travels 5 metres the man travels 5(1 +- 2^1/2)/1 m. Distance cannot be negative. So, the distance traveled by the soldier = 5(1 + 2^1/2) m.

Ethan

11:02 AM

This chat has LaTeX support