Question

solve the system using matrices (Gaussian elimination method). if there is no solution or if the systems equation dependent, so state ?

x + y + z = 9
x - y + 5z = 17
2x + y + z = 13

Answer 1

matrix it up and row reduce ....

Answer 2

if you get a row that is inconsistent; its bad; otherwise there are solutions

Answer 3

how

Answer 4

how what? how to you form a matrix? how do you perform elementary matrix operations? how do you ... what?

Answer 5

i assume since you ask the question that your familiar with at least some of these processes and are not actually wanting to know all the stuff about matrices

Answer 6

well this is a take home test, so i dont wana give it to her and its wrong answer

Answer 7

im tring to get the answer so i compare it to mine wen i try attempt to solve it

Answer 8

there are 3 elementary row operations that can be done on a matrix; do you recall what they are?

Answer 9

yeahh

Answer 10

if we know those operations we can then strip all the stuff from our equations and keep only numbers and signs:

x + y + z = 9
x - y + 5z = 17
2x + y + z = 13

becomes the matrix

1 1 1 9
1 -1 5 17
2 1 1 13

Answer 11

what are our 3 elementary row operations that we can do?

Answer 12

yep i did that arledyy

Answer 13

, -1 5
1 1

Answer 14

-1(5) + 1(1)

Answer 15

you trying to cramer this thing up? thats madness

Answer 16

oh my bad lol, sorry got confused lol

Answer 17

1 1 1 9
1 -1 5 17 ; *-1
2 1 1 13 ; /-2


1 1 1 9
-1 1 -5 -17
-1 -1/2 -1/2 -13/2


1 1 1 9
0 2 -4 -8
0 1/2 1/2 5/2


1 1 1 9
0 2 -4 -8 ; /2
0 1/2 1/2 5/2 ; *-2


1 1 1 9
0 1 -2 -4
0 -1 -1 -5

1 1 1 9
0 1 -2 -4
0 0 -3 -9 ; /-3


1 1 1 9
0 1 -2 -4
0 0 1 3

well, the good noews is its consistent

Answer 18

wow thanks man, thats the hole thing ?

Answer 19

you really dont know whats going on with this do you ....

Answer 20

thats just half of it

Answer 21

honestly i have no idea man. im not gona lie and say i do.

Answer 22

this is a take home test and im tring to get this right.

Answer 23

the matrix method is not a good way to do by hand; elimination and substitution are the way to go if your doing it by hand

Answer 24

so far, all ive done is get this to a row eschelon form; I still have to reduce it by getting 0s above all my 1s to read off the unique solution on the right side

Answer 25

im so lost lol. im tring to rite this down and im like 0.0

Answer 26

1 1 1 9
0 1 -2 -4
0 0 1 3 .... z = 3

1 1 1 9
0 1 0 -4 -2(3) = -10; y=-10
0 0 1 3 .... z = 3

1 0 0 9 -(3)+(10) = 16
0 1 0 -10 ... y=-10
0 0 1 3 .... z = 3


1 0 0 16 ... x = 16
0 1 0 -10 ... y=-10
0 0 1 3 .... z = 3


now the best thing to do is dbl chk it with something that can handle the repetitive nature; like a computer :)

Answer 27

rref[1, 1, 1, 9;1, -1, 5, 17;2, 1, 1, 13]

lets see if the wolf like this :)

Answer 28

lmao, see if u did mma, or hit the gymm with me i woulda helped u lmao. but as u can see im retricein this.

Answer 29

i ment im garabge lol

Answer 30

http://www.wolframalpha.com/input/?i=rref%7B%7B1%2C+1%2C+++1%2C+++9%7D%2C%7B1%2C++-1%2C++5%2C++17%7D%2C%7B2%2C+++1%2C+++1%2C++13%7D%7D

wolf like a different format; but it says I missed the mathing someplace

Answer 31

1 1 1 9
0 1 -2 -4
0 0 1 3 ; *2, *-1

1 1 1 9
0 0 -1 -3
-----------------
1 1 0 6

0 1 -2 -4
0 0 2 6
-----------------
0 1 0 2




1 1 0 6
0 1 0 2 :*-1
0 0 1 3




1 1 0 6
0 -1 0 -2
--------------
1 0 0 4




1 0 0 4
0 1 0 2
0 0 1 3


so our solutions are: x=4, y=2, amd z=3

Answer 32

thatll teach me to try something new lol

Answer 33

lmao i dont even noe wat to rite to show work. LOL

Answer 34

and unless you know what im doing, this will make absolutely no sense ... :)

Answer 35

look thru your material to see how it shows the row operations and see if you can line some things up according to the format your material provides you with

Answer 36

okk ima chek but can u stick around to help me ? you will be my life savor lol.

Answer 37

i got school work to catch up on too, but if im around ill see what i can do within reason

Answer 38

okaay thankss lovee. big help !

Answer 39

as i said prior; this question itself presupposes that you have some idea as to whats going on. otherwise there is too much behind the scenes work to try to explain

Answer 40

yeah i noe im looking at it now, but thanks alot. im cheking and reviewing it now