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Math1004: discrete maths (2 Viewers)

Collin

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I agree, I'm doing 3 maths this semester, and to relieve the burden a bit I fucked off Physics. For good. I don't need it for my majors anyway, and I hate it. Only problem is I spent $120 on that damn fat textbook, but hey.. I can't win everytime.
 

Bob.J

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im in 2nd year doing 4 maths and physics. I know some people doing 6 maths along with physics. Now thats nasty
 

comfortable

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yeah omg discrete is boring!!! all we do in lectures is write pages and pages of notes :( but im pretty happy with the quiz we just had, that was alright...mainly coz it was multiple choice ;) btw has neone started the assignment? im stuck...
 

BlackJack

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Look you can post a question up, one of us might have a look at it and give some clues. I *think* I remember my discrete well enough.
---
Well keypad, I can't really imagine how they'd teach an advanced version of number theory anyway...
 

comfortable

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oh ok kool! basically i cant do much of it, but i think that once ive got one part done i can figure out the rest :)

"how many distinguishable strings can be made using EXACTLY 10 letters in the 11 letter word NECESSITATE? no letter may occur more often in a string than it occurs in the word."

ne help would be appreciated!
 

BlackJack

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A sure way to do this would be to sum up your possible configurations.

You should sort out first how many of each letter you do have. (Say, 3Es, 2 of S&T,one of each of the rest).
Ask yourself what would be the possible arrangements if I say, took away one E and use the other 10 letters to make a string? This is one case. Then proceed with taking out other letters (non E, you've already done that case) until you obtain the answer for each case.
 

Saul

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isn't it along the lines of 11!/3!2!2! yaaaaaawn... i figure this cause if you had 11 different letters you'd just have 11! different ways of doing it (not 10!), but cause you repeat the e 3 times and the s and t 2 times you have to divide by that... i could be wrong - i mean it is fairly early and all.
 

BlackJack

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The extra condition here is that you're NOT using one of the letters, and it could be any one of them.
There may be a shorter way of doing this, but it's more intuitive than explicit. It goes along the line of having one place in the word reserved for your deleted letter and doing one calculation.
 

Saul

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oh ohoh, but doesn't not using a letter not have a difference? cause if you dont use a letter you may as well be shoving that letter on the end, its still being specified as the one not being used. if it said make a 9 letter word it'd be different.
 

comfortable

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ooooooooooooooh ok kool...but thats not the answer is it? because 11!/3!2!2! would b too easy...
 

BlackJack

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comfortable said:
ooooooooooooooh ok kool...but thats not the answer is it? because 11!/3!2!2! would b too easy...
These assignments last year were indeed very easy, so I thought they might also give marks to your logic if ithe question was worth more.
You should say that you realise taking one letter away is equivalent to placing it at the back, or whatever steps you take (in succint terms) to derive the answer, just in case.
 

Collin

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5 weeks on and I honestly hate discrete maths, but statistics is even worse. Permutations and combinations was a nightmare for me in 3 unit (not because I couldn't do them, but because I hated the topic). Atleast integral calculus is still jolly fun.
 

Saul

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anybody care to throw a little love my way on question 1) iii) ?
 

tooheyz

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we should be getting the assignment back sometime this week
yay :)

dont u guys just love the stuff we're doing now? hahah mechatronics people did all this in our mechatronics tutorials

:)
 

Carlito

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tooheyz said:
we should be getting the assignment back sometime this week
yay :)

dont u guys just love the stuff we're doing now? hahah mechatronics people did all this in our mechatronics tutorials

:)
yeah i did it last semester in elec, but it was slightly different, as in we used some different notation
 

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