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Hi guys just some quick questions (need answered asap please )
(i) Prove that in any digraph with p vertices
p-1 >= RC(u) >= 1-p Where RC(u) = outreach(u) - inreach(u) and u is some vertex.
(ii) Prove that in any acyclic digraph, if (u,v) is an arc then RC(u)>RC(v)
(iii) Prove that if u is any source in an acyclic digraph and v is a sink, then
RC(u)>=RC(v)
under what circumstances can equality occur.
Thanks guys=)
Bobbym, brilliant and modest
Hi mathsyperson, I'm just as confused as you are
An example of one we did in class is :
Show that
is
forsince log is increasing
So if someone could maybe go through this one, it would be much appreciated, cheers=)
Find
And maybe even (if you're feeling lucky )
Let f(n) = n^2 and g(n) = 2n^2. Find O(g(n)-f(n))
Thanks for your time
For the question:
Give a basis for the vector space V and find the dimension of V
I could only find x in which this would work.
So would the basis be {x}??
I would appreciate some guidance rather than a direct answer(if this is possible=)) since this is an assignment question.
Thanks all
Hey guys just need some help with this one, thanks.
(a) If
andshow that
Well yeah different notation in different countries i guess haha
Hi;
now finally R2 - R1
Do I store R2-R1 back into R2?
Umm yeah so like R2---> R2 - R1
if that makes sense=)
Solution:
is a nonempty set because it contins the zero vector 0.(i.e. Let)
Let u and v be in
Say,
and
Then
So u+v is also in
(because it has the right form)Siilarly if k is a scalar, then
So ku is in
Thus,
is a nonempty set of that is closed under addition and scalar multiplication. Therefore, is a subspace of , by Theorem 5.2Nevermind i think i've got it, I'll post my solution tomorrow.
This is Theorem 5.2
Let V be a vector space and let W be a nonempty subset of V. Then w is a subspace of V if and only if the following conditions hold:
a. If u and v are in W, then u + v is in W.
b. If u is in W and c is a scalar, then cu is in W.
Now for the question:
In exercise 25, use Theorem 5.2 to determine whether W is a subspace of V.
Can someone please explain to me what is going on here, thanks (if it makes a difference the column vector above is also ment to have squigly brackets around it, but i couldnt do that AND the parenthesis.)
Ok after a little thought power i managed to solve it....
From MATLAB B*A is:
Now we simply set up the equations
and solve each one for c1 c2 c3 by augmenting each system of equations and using rref or back substitution...
for the first equation:
will do.
for the second equation:
will do.
and lastly, for the third equation:
will do.
So we have written each column of BA as a linear combination of the columns of B.
Hi can anyone explain a method to solve this problem
let A,B be two matrices where
A=[1,0,-2;-3,1,1;2,0,-1] (where ; seperates the rows of the matrix)
B=[2,3,0;1,-1,1;-1,6,4]
Use the matrix-column representation of the product to write each column of BA as a linear combination of the columns of B.
cheers guys
the first row operation will be...
minus R1 from each of R2 through to Rn
then
divide all rows from R2 through to Rn by n
then
minus (n-1)R2 from each R3 to Rn (where n is the row number i.e. a constant)
now finally R2 - R1
to get....
[1 2 3 ... n]
[0 -1 -2 ... 1-n]
[0 0 0 ... 0]
[0 0 0 ... 0]
etc etc
which is the given nxn matrix in row echelon form (i think haha)
I'm having a few troubles with 'validly deduce'
Here is the question:
Q: For any set S of sentences, if T is a tautology, then you can validly deduce T from S.
Can anyone explain to me what it is to 'validly deduce' something, pretty confused here, cheers
Umm i'm not going to bother posting what i got unless anyone actually wants the answer if so speak up.
yeah i think i got a bit confused=/ let me get back to you haha
just a quick question and sorry for being messy =/
[ 1 2 3 ... n ]
[ n+1 n+2 n+3 ... 2n ]
[ 2n+1 2n+2 2n+3 ... 3n ]
[ . . ]
[ . . ]
[ . . ]
[(n^2 -n +1)(n^2 -n +2) (n^2 -n +3) ... n^2 ]
I am asked to find the row echelon form of the nxn matrix.
What i did is minused n from row 2 then minused 2n from row 3 and so on... untill the last row where i minused (n-1)n
this gave me an nxn matrix with identical rows containing 1 2 3 ... n
Would this be sufficent as the row echelon form of the matrix or simplify it further?
Thanks in advance for the help
ok thanks so much bobbym that helped lots
Umm yes please that would be great if you dont mind
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