math 1002: linear algebra (1 Viewer)

[Carlito]

arghhh i havnt even started yet ive been working all weekend, shit it looks so confusing

 

[Adam]

How do you do 1)ii)??

Is a) just:

x1 + 3x4 = -1
x2 + +2x4 = 4
x3 -3x4 = 3

And then take x4 to be the free variable?

And with b), what the hell is different?

 

[Winston]

Originally posted by Adam
How do you do 1)ii)??

Is a) just:

x1 + 3x4 = -1
x2 + +2x4 = 4
x3 -3x4 = 3

And then take x4 to be the free variable?

And with b), what the hell is different?

have u done 1 i yet?

yep for 1 ii u take x4 as a free variable and solve its easy

as for the second part of it, it's not augmented and it's a homongenous system, so thus they all equal to 0, so let them equal to 0 and augment it, and then you should have two free variables and yeah just solve.

 

[Adam]

Well I've got 1)i) into a dandy RREF, but I have no idea what it means with a)b)c).

 

[Winston]

Originally posted by Adam
Well I've got 1)i) into a dandy RREF, but I have no idea what it means with a)b)c).

can u show me wat RREF u got cause im not sure if i got the right one.

 

[JUB JUB]

Originally posted by Winston
have u done 1 i yet?

yep for 1 ii u take x4 as a free variable and solve its easy

as for the second part of it, it's not augmented and it's a homongenous system, so thus they all equal to 0, so let them equal to 0 and augment it, and then you should have two free variables and yeah just solve.

so practically it's the same working out except each line actually equals 0 originally instead of -1,4 and 3? so we now can put in 2 letters in place of x3 and x4?

 

[Carlito]

omg so much matrix multiplication for the last question., but its like the only question i can do

 

[lm1122]

ARGH

 

[Adam]

[-2+3a 0 0 | 3b-6 ]
[0 1 0 | 3]
[a-1 0 1 | b+1]

But I am not sure either...

HELP!?

 

[Carlito]

thts not echelon form??? is it?

 

[JUB JUB]

hey guys for 1)ii)a) when u start to the lines equal 0 -so that the first line will equal 1. or do they equal the 4th term there....-1 ?

Originally posted by Carlito
omg so much matrix multiplication for the last question., but its like the only question i can do

yeh that was such a bitch

 

[Wyvern]

how do you do question 2 part ii? what part of the book is it?
I am not sure how to start it

ive done the rest if anyone needs any help

 

[Wyvern]

Originally posted by JUB JUB
hey guys for 1)ii)a) when u start to the lines equal 0 -so that the first line will equal 1. or do they equal the 4th term there....-1 ?

pretty sure its equals -1

 

[Carlito]

Originally posted by Wyvern
how do you do question 2 part ii? what part of the book is it?
I am not sure how to start it

Question 2 part ii is just mainly matrix multiplication

The first part (a) about the elemetray matrices is just doing the ERO on the identity matrix. eg E2 = the identiy matrix with row 1 and 3 swapped. Part (b) is just their inverse.

I have done everything except for all of 1.(i) and the second part of 2.(i)

 

[Wyvern]

for second part of 2 (i)........to solve the linear system
you multiply the inverse of A by
1
-1
2

just like they do on page 56

 

[JUB JUB]

Originally posted by Wyvern
pretty sure its equals -1

thanks mate

Originally posted by Wyvern
how do you do question 2 part ii? what part of the book is it?
I am not sure how to start it

ive done the rest if anyone needs any help

if u look at one of the tutes...can't remember which...there is a very similiar question =)

 

[Winston]

Which questions are people stuck on? I finished it .

 

[Carlito]

Originally posted by Winston
Which questions are people stuck on? I finished it .

Question 1.(i) ... I cant even reduce it to echalon form let alone understand what they want me to do after that.

 

[Winston]

Originally posted by Carlito
Question 1.(i) ... I cant even reduce it to echalon form let alone understand what they want me to do after that.

hmmm try reducing it to the best u can and tell me where u stop at.

 

[Carlito]

what do i do with the 'a'