Question

find the system of equations
x-y+z=2
x+y+z=4
y+2z=3

Answer 1

@agent0smith

Answer 2

Subtract the second equation from the first.

Answer 3

Or add them :3

Answer 4

If you want to do more work, then sure, add them ;)

Answer 5

Crud... really need to pay attention to details >.>

Answer 6

hehe :) if you don't like negatives, subtract the first equation from the second.

Answer 7

okay so umm I see no x y or z's like to help me get started ._.

Answer 8

why not a simple substitution the 3rd equation

y = 3 - 2z

then substitute it into the 1st and 2nd equations and you will have 2 equations in 2 unknowns, x and z.

Solve then by elimination

Answer 9

oh.. apologies :)
What agent smith meant about subtracting equations is as follows:
Say, you have two equations
\[\Large \color{blue}{x+y} = \color{red}9\]\[\Large \color{blue}{x-y}=\color{red}{-4}\]
Then, say, to subtract the second equation from the first, you just subtract the left-sides, and equate it to the difference of the right-sides...
\[\Large (\color{blue}{x+y})-(\color{blue}{x-y})=\color{red}{9}-\color{red}{(-4)}\]
\[\Large \color{blue}{2y=\color{red}{13}}\]

Answer 10

x-y+z=2
x+y+z=4
y+2z=3

subtract the first from the second to get:

x-y+z=2
2y=2
y+2z=3

now it's easy.

Answer 11

Right, I shall steer clear now, lest I confuse the OP :)

Answer 12

Because @campbell_st elimination is faster and easier.