Question

It's pretty pathetic when I can't even do substitution for equations and everyone says I am the smart kid!! :(. Help? It's pretty pathetic when I can't even do substitution for equations and everyone says I am the smart kid!! :(. Help? @Mathematics

Answer 1

911?

Answer 2

yes...
(x+y+z=2)
(x+2z=5)
(2x+y-z=-1)

Answer 3

thats ok, i cant do diffy qs to well and im a veritable genius lol

Answer 4

we can see that x = 5-2z from the 2nd eq

Answer 5

sub that into the others

Answer 6

haha.

Answer 7

all a system of equations is is saying that there are common values for the variables

Answer 8

as such, we can substitute "quasi" values and come up with solid values

Answer 9

since x has to equal 5-2z; we can simply use that in the other equations to simplify matters

Answer 10

uhmm well i dont know what quasi is lol

Answer 11

quasi means .... youre gonna make me look up my own words aintcha

Answer 12

http://www.google.com/search?aq=f&gcx=c&sourceid=chrome&ie=UTF-8&q=quasi

Answer 13

having the appearance of, resembling, related to in some fashion that is not concretely established

Answer 14

haha i guess so. :)

Answer 15

x+y+z=2

x+2z=5 <-- x = 5-2z

2x+y-z=-1
.........................................

substitute it in

(5-2z)+y+z=2

x = 5-2z

2(5-2z)+y-z=-1

........................................

"solve"

5-2z+y+z=2
5-z+y = 2

x = 5-2z

2(5-2z)+y-z=-1
10-4z+y-z = -1
5z+y = -11

etc

Answer 16

the 2 new eqs that result can be compared for either z or y now


5-z+y = 2
-z+y = -3
y = z-3
.................................

substitute this "value" since its got to hold for all ys

5z+y = -11
5z+(z-3) = -11
5z+z-3 = -11
6z = -8

z = -4/3 if im right

Answer 17

okay this is what i have

Answer 18

and since y = z-3, and z=-4/3

y = -4/3 -3

y = -13/3

i hate fractions they always make me worry

Answer 19

and of course we had: x = 5-2z, and z=-4/3

x = 5-2(-4/3)
= 5+ 8/3
= 23/3

maybe

Answer 20

(x+y+z=2)
(x+2z=5)
(2x+y-z=-1)
x=-2z+5
-2z+5+y+z=2
-z+y=-3
y=z-3
2(-2z+5)+z-3-z=-1
-4z+10+z-3-z=-1
am i doing any of this right?

Answer 21

i messed it up someplace since the wolf disagrees with me ;)

http://www.wolframalpha.com/input/?i=%28x%2By%2Bz%3D2%29+and++%28x%2B2z%3D5%29+and+%282x%2By-z%3D-1%29

Answer 22

that looks good

Answer 23

from what i can parse from it

Answer 24

okay then i might have this...but i might still be coming back for more help. :)

Answer 25

right here is my mess:

2(5-2z)+y-z=-1
10-4z+y-z = -1
5z+y = -11 <-- should be -5, i dropped me sign :/

Answer 26

okay i figured it out lol. Thanks for the help. :).

Answer 27

You will probably be getting a lot of medals from me btw lol.

Answer 28

i already got lots of medals ;) but thnx anyhoos