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Xarpolis
RealPoor Guru
Joined: 15 Oct 2002
Posts: 2884
Location: Philly, PA
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 Posted: 11/29/03 - 10:52 Post subject: Hey Math people! how good are you?
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If a = [15,10] and B = {x, y, z}, find A * B, B * A and N(A * B)
I think they just want a tree diagram or something. no, this isn't for me, it's a question someone just asked me to help him figure out, but I suck so... I came here!
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Mogling
RealPoor Guru
Joined: 29 Dec 2002
Posts: 2451
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Posted: 11/29/03 - 10:53 Post subject:
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A is a vector and b is a set of scalar values?
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BlingBling
Toomuchtimeonhands
Joined: 20 Dec 2002
Posts: 947
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Posted: 11/29/03 - 10:57 Post subject:
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If a = [15,10] and B = {x, y, z}
this isnt written in correct form
a would be a column vector [15,10] and {} means what?
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Xarpolis
RealPoor Guru
Joined: 15 Oct 2002
Posts: 2884
Location: Philly, PA
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Mogling
RealPoor Guru
Joined: 29 Dec 2002
Posts: 2451
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Posted: 11/29/03 - 11:16 Post subject:
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{} usualy means a set, also what is N?
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Mogling
RealPoor Guru
Joined: 29 Dec 2002
Posts: 2451
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Posted: 11/29/03 - 11:17 Post subject:
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Cross products are sooo not muliplication....
at least thats what they look like....
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BlingBling
Toomuchtimeonhands
Joined: 20 Dec 2002
Posts: 947
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Posted: 11/29/03 - 11:33 Post subject:
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ya thats all f****d up
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BlingBling
Toomuchtimeonhands
Joined: 20 Dec 2002
Posts: 947
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Posted: 11/29/03 - 11:35 Post subject:
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a x b is [5x+5y+5z; 10x+10y+10z]
b x a is [15x ; 15y ; 15z]
for N() just mulitply through by N
assuming they mean that both a and b are colum vectors, this should be correct
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Krumble
Toomuchtimeonhands
Joined: 11 Oct 2002
Posts: 771
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Posted: 11/29/03 - 11:48 Post subject:
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Cross product defines a vector that is perpendicular to both vectors being crossed and with a magnitude that is equal to the area of their determinant. So the cross product of (a x b) would be a 3d vector, I think. Wouldn't you assume that a has a z value of 0?
If that's the case, (a x b) = {10z, -5z, 5y - 10x}
and (b x a) would be = {-10z, 5z, 10x - 5y}
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BlingBling
Toomuchtimeonhands
Joined: 20 Dec 2002
Posts: 947
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Posted: 11/29/03 - 18:25 Post subject:
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well, if we assume those are i j k components you are correct
if they are not i j k values than we have to assume they are vectors, used in linear algebra, the X may just mean multiplication,
in this case the results i gave are correct
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Ursar
Luke Warm
Joined: 12 Oct 2002
Posts: 134
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Posted: 11/29/03 - 19:46 Post subject:
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NinjaBurger
RealPoor Guru
Joined: 01 Sep 2003
Posts: 2800
Location: St. Louis
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Posted: 11/29/03 - 20:51 Post subject:
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What
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Thuphir
Luke Warm
Joined: 15 Oct 2002
Posts: 206
Location: Baton Rouge
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Posted: 11/29/03 - 21:01 Post subject:
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Xarp if your friend (wink wink, nudge nudge) needs help with this 'problem' tell him he needs to start studying or drop ;p
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Xarpolis
RealPoor Guru
Joined: 15 Oct 2002
Posts: 2884
Location: Philly, PA
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Posted: 11/29/03 - 21:06 Post subject:
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Dude, it was Biny in #fires on IRC.
I just told him I'd ask a few people for help, 'cause I didn't know.
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Yabden
RealPoor Guru
Joined: 13 Oct 2002
Posts: 2485
Location: Ohio
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Posted: 11/30/03 - 00:09 Post subject:
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7.2!
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ATM Banana
RealPoor Master of Posts
Joined: 02 Jan 2003
Posts: 8575
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Posted: 11/30/03 - 00:54 Post subject:
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haha... i lvoe your yab
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Mental_Hernia
RealPoor Guru
Joined: 14 Oct 2002
Posts: 3336
Location: Texas
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Posted: 11/30/03 - 00:55 Post subject:
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| BlingBling wrote: | If a = [15,10] and B = {x, y, z}
this isnt written in correct form
a would be a column vector [15,10] and {} means what? |
For how dumb you tend to come off as, I don't understand how you know a lot of the stuff that you do no
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Kantiz
Sir Postalot
Joined: 13 Oct 2002
Posts: 1267
Location: Harrisburg, PA
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Posted: 11/30/03 - 01:06 Post subject:
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in life, there's those with book smarts, and those with street smarts
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ATM Banana
RealPoor Master of Posts
Joined: 02 Jan 2003
Posts: 8575
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Posted: 11/30/03 - 01:07 Post subject: Re: Hey Math people! how good are you?
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| Xarpolis wrote: | If a = [15,10] and B = {x, y, z}, find A * B, B * A and N(A * B)
I think they just want a tree diagram or something. no, this isn't for me, it's a question someone just asked me to help him figure out, but I suck so... I came here! |
xarp, how old are you?
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Xarpolis
RealPoor Guru
Joined: 15 Oct 2002
Posts: 2884
Location: Philly, PA
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Posted: 11/30/03 - 01:10 Post subject:
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22 sir. What's up?
And might I add in yet again, that this isn't for me. If I remember back to my years of highschool, I honestly don't remember doing vectors or anything of the sort. That falls under Calcalus, I'd assume?
Biny (the person who asked me the question in the first place) said that it was for his Logic Class, what ever that would be.
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NinjaBurger
RealPoor Guru
Joined: 01 Sep 2003
Posts: 2800
Location: St. Louis
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Posted: 11/30/03 - 02:02 Post subject: Re: Hey Math people! how good are you?
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| Xarpolis wrote: | If a = [15,10] and B = {x, y, z}, find A * B, B * A and N(A * B)
I think they just want a tree diagram or something. no, this isn't for me, it's a question someone just asked me to help him figure out, but I suck so... I came here! |
The answer is 42.
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atarom
Guest
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Posted: 11/30/03 - 02:07 Post subject:
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hey do you have that song ninja?
about how 42 is the answer to the universe?
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NinjaBurger
RealPoor Guru
Joined: 01 Sep 2003
Posts: 2800
Location: St. Louis
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Posted: 11/30/03 - 02:18 Post subject:
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That was from the Hitchiker's Guide to Space wasn't it?
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ATM Banana
RealPoor Master of Posts
Joined: 02 Jan 2003
Posts: 8575
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Posted: 11/30/03 - 02:42 Post subject:
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my friend used to say that a lot when i presented him with complicated problems, which didn't actually use any coeficients, just variables, he would still say "42" which made me angry enough to block him for 2 months, then realize 1 month and 3 weeks too late that he was still blocked.
= /
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atarom
Guest
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Posted: 11/30/03 - 02:45 Post subject:
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no i heard this techno song and it was all about how 7 x 6 is 42 and 4 x 2 = 6 and 6 x 4 was 24 and 2 + 4 = 6 and shit.
and i was like WHOAH MAN THAT"S DEEP.
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NinjaBurger
RealPoor Guru
Joined: 01 Sep 2003
Posts: 2800
Location: St. Louis
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Posted: 11/30/03 - 02:48 Post subject:
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Never heard of it.
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ATM Banana
RealPoor Master of Posts
Joined: 02 Jan 2003
Posts: 8575
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Posted: 11/30/03 - 02:59 Post subject:
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maybe because you didn't imagine it as well.
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NinjaBurger
RealPoor Guru
Joined: 01 Sep 2003
Posts: 2800
Location: St. Louis
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Posted: 11/30/03 - 03:02 Post subject:
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NO I THOUGHT OF STRONG BAD'S TECHNO!
And Tecknoe Destructo.
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atarom
Guest
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Posted: 11/30/03 - 06:57 Post subject:
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the system is down.
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Spitulski
RealPoor Guru
Joined: 23 Nov 2002
Posts: 4344
Location: Washington
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Posted: 11/30/03 - 10:42 Post subject:
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light-switch rave
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