Please tell me

HopeYouKnowWhoIam · 2014-09-23 17:50:00

Please tell me if Coefficient[Product[(x+i),{i,100}],x,99] is 5050 because no CAS is working here?! help!!!!

Bob · 2014-09-23 18:40:30

hi HopeYouKnowWhoIam

Welcome to the forum. I, for one, don't know who you are.

I also don't follow your syntax. What are you multiplying (x + i) by ?

Bob

anonimnystefy · 2014-09-23 18:49:45

Hi Bob

It's M syntax. I'll try to run it, he basically wants the x^99 term of

Last edited by anonimnystefy (2014-09-23 18:55:04)

Bob · 2014-09-23 18:54:15

hi Stefy,

Thanks, I did wonder if that was the sort of thing meant.

Now is that i the 'summation' variable Ie the same as n in your version ?

Bob

Bob · 2014-09-23 18:56:13

What I mean is

is this (x+1)(x+2).....(x+100) or is it (x+i)^100 where i is a constant ?

Bob

anonimnystefy · 2014-09-23 18:56:48

Yes, it is, I have edited it accordingly.

If I am not mistaken, the x^99 term should be

Bob · 2014-09-23 19:00:34

The x^99 term will be found by picking 99 brackets with x and one bracket with a number and then adding them up. So the coefficient is

Who needs a CAS ?

Bob

anonimnystefy · 2014-09-23 19:06:45

Ah, yes, that is correct. I was thinking of the x term.

Have you seen the thread that emerged?

Bob · 2014-09-23 19:27:41

Have you seen the thread that emerged?

?? Which thread ?

btw re-check your Latex in post 6.

Bob

anonimnystefy · 2014-09-23 19:33:55

What's wrong with my LaTeX?

What's my line?

Agnishom · 2014-09-23 19:44:51

Thank you, guys. It indeed is 5050. I did with combinatorics, I do not get the normal procedure anyway

anonimnystefy · 2014-09-23 20:02:25

Is this a Brilliant problem?

Bob · 2014-09-23 20:13:58

Stefy wrote:

What's wrong with my LaTeX?

This is what I'm seeing:

So what is 1/i when i = 0 ?

Bob

Agnishom · 2014-09-23 20:16:03

It is not a Brilliant problem. But it will become one soon.

The next knows how

anonimnystefy · 2014-09-23 20:19:32

That's no a Latex problem, it's me not checking. It should go from i=1 and is the answer for the incorrect problem.

Yes, I know.

bobbym · 2014-09-23 21:14:37

Hi HopeYouKnowWhoIam;

I know who you are. Someone who ain't been reading my computer math thread.

Coefficient[Product[(x + i), {i, 100}] // Expand, x^99]

is 5050 because no CAS is working here

There ain't nuthin a CAS can not do.

Agnishom wrote:

It is not a Brilliant problem. But it will become one soon.

Hoooha, I can not wait.

Agnishom · 2014-09-23 21:42:25

The command he posted works too:

Coefficient[Product[(x+i),{i,100}],x,99]

bobbym · 2014-09-23 21:47:09

It does not work.

Agnishom · 2014-09-23 21:52:21

In[1]:= Timing[Coefficient[Product[(x + i), {i, 100}], x, 99]]

Out[1]= {21.056764, 5050}

The OP is following your Computer Math thread. He could not get the CAS to work because he did not have it on the machine which he was using then.

bobbym · 2014-09-23 21:54:32

I repeat, that does not work. Efficiency counts.

AbsoluteTiming[Coefficient[Product[(x + i), {i, 100}], x, 99]]

AbsoluteTiming[Coefficient[Product[(x + i), {i, 100}] // Expand, x^99]]

Agnishom · 2014-09-23 22:00:30

bobbym wrote:

Mathematicians like simplicity. I like speed. Your solution is neither simple nor fast.

bobbym · 2014-09-23 22:03:30

It is over 40 times faster than the OP's solution on my machine! Please run the code.

Agnishom · 2014-09-23 22:09:09

In[2]:= AbsoluteTiming[Coefficient[Product[(x + i), {i, 100}], x, 99]]

Out[2]= {20.849901, 5050}

In[3]:= AbsoluteTiming[
 Coefficient[Product[(x + i), {i, 100}] // Expand, x^99]]

Out[3]= {0.008456, 5050}

In[5]:= %2/%3

Out[5]= {2466., 1}

Do you know why he could not get the CAS working?

bobbym · 2014-09-23 22:12:08

You seem to be agreeing with me... My solution is much faster and we can do better.

Do you know why he could not get the CAS working?

Who, what, when please.

Agnishom · 2014-09-23 22:32:26

Who

I am talking about the OP.

when

Today 11:20 Indian Standard Time

what

What what?

Math Is Fun Forum

#1 2014-09-23 17:50:00

Please tell me

#2 2014-09-23 18:40:30

Re: Please tell me

#3 2014-09-23 18:49:45

Re: Please tell me

#4 2014-09-23 18:54:15

Re: Please tell me

#5 2014-09-23 18:56:13

Re: Please tell me

#6 2014-09-23 18:56:48

Re: Please tell me

#7 2014-09-23 19:00:34

Re: Please tell me

#8 2014-09-23 19:06:45

Re: Please tell me

#9 2014-09-23 19:27:41

Re: Please tell me

#10 2014-09-23 19:33:55

Re: Please tell me

#11 2014-09-23 19:44:51

Re: Please tell me

#12 2014-09-23 20:02:25

Re: Please tell me

#13 2014-09-23 20:13:58

Re: Please tell me

#14 2014-09-23 20:16:03

Re: Please tell me

#15 2014-09-23 20:19:32

Re: Please tell me

#16 2014-09-23 21:14:37

Re: Please tell me

#17 2014-09-23 21:42:25

Re: Please tell me

#18 2014-09-23 21:47:09

Re: Please tell me

#19 2014-09-23 21:52:21

Re: Please tell me

#20 2014-09-23 21:54:32

Re: Please tell me

#21 2014-09-23 22:00:30

Re: Please tell me

#22 2014-09-23 22:03:30

Re: Please tell me

#23 2014-09-23 22:09:09

Re: Please tell me

#24 2014-09-23 22:12:08

Re: Please tell me

#25 2014-09-23 22:32:26

Re: Please tell me

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