Perms and Combs (1 Viewer)

[velox]

In how many ways can 4 consonauts and 3 vowels be arranged in a row if (b) so that the first and the last places are occupied by consonauts?

 

[Archman]

4!*3!*5c3.

 

[velox]

hmmm y?...?

 

[Archman]

4!: ways to arrange the consonants
3!: ways to arrange the vowels
5C3: ways to put the vowels since they cant be first or last.

 

[Trev]

i hate perms n combs i suck at them, alot of them cant really be proven can they?!....i dont think we should learn stuff that isnt proven lol

 

[Archman]

na, its all proven, way more proven than lots of the physics crap u may learn.

*cramming for phys*

 

[withoutaface]

i hate perms n combs i suck at them, alot of them cant really be proven can they?!....i dont think we should learn stuff that isnt proven lol

You find for me more or less than 4!3!5C2 combinations from that question and then we'll talk.

 

[velox]

what about this question:

11. Father, mother and 6 children stand in a ring. In how many ways can they be arranged if the father and mother are not to stand together?

 

[Archman]

fix the mother, there are 5 places to insert the father (no, its not what you think), and 6! ways the kids can fit in.

so 5*6!

 

[velox]

thanks Hmm they seem to be easy, but i cant get my head around them

 

[Trev]

oh..... lol, its still the devil!

 

[withoutaface]

find arrangements of 5 women and 3 men in 8 places (in a row)?

8!(the numbers of men and women are a red herring)

 

[velox]

yeah i read the question wrong, hence got the wrong answer

 

[nick1048]

Induction is annoying me... and I've only started yr 12... BAKA 4 UNIT KILLS 3 UNIT!!! GO TO HELL 3 UNIT!

 

[velox]

induction is alrite, but i hate writing an essay every time i do a question

 

[withoutaface]

This is all you need for conculsion:

:. S(k) true implies S(k+1) true
But S(1) is true
:. by induction, true for all integers n>=1

 

[mojako]

This is all you need for conculsion:

:. S(k) true implies S(k+1) true
But S(1) is true
:. by induction, true for all integers n>=1

you need to define S(n) at the very start first.
also, you don't need to write "by induction" at the end

 

[withoutaface]

you need to define S(n) at the very start first.
also, you don't need to write "by induction" at the end

well pfffft to you

 

[Slidey]

I still don't understand the difference between the weak and storm forms of induction.

 

[TripleJ]

And here I was expecting a thread on hair care!