Question

I've been going at this for hours now and simply can't grasp the concept. If you need a question answered, feel free to send them my way. Thanks!


Use the substitution method to solve the following system of equations.

x + 2y - z = 7
4x - y + 3z = -2
2x + 2y - z = 9


ANSWER CHOICES:

(2, 1, 3)

(2, 1, -3)

(-2, 1, -3)

(-2, -1, 3)

Answer 1

substitution method means you solve one equation for a single unknown and substitute (or replace) this into another equation for that unknown. This will drop the number of unknowns down by one. For three equations we need to do this twice. It will get messy so take your time to eliminate stupid mistakes. Do you need step by step help?

Answer 2

Oh my, I appreciate that thorough response of yours, thank you

Answer 3

And if you wouldn't mind, that would be grand!

Answer 4

I made a mistake of my own earlier on when trying to solve this equation, so you're definitely right about that! :)

Answer 5

lets start with equation 1 and solve it for x. I chose this first because x is already positive and by itself. Tell me what you get

Answer 6

I was taught to subtract the first equation from the third, getting a -2 I believe, however, I'm not sure if that helps me find my answer

Answer 7

That is the easier method. It is called elimination method. It is where you can completely eliminate a variable. Did your teacher say that? When I read the question i was thinking substitution only. If we are allowed to do that, it would make it easier on us

Answer 8

Yes

Answer 9

Oh, in the problem it recommends the use of the elimination method

Answer 10

So far I have -2, but I'm wondering what I have to do to figure out the other digits?

Answer 11

I have x=2, watch your negative signs

Answer 12

My error

Answer 13

My answer choice I got is B

Answer 14

Correct!!

Answer 15

oh my gosh thank you so much for your help!!!!!!!!!!!!!!!!!!!! @ChmE

Answer 16

you're such a great helper, really! :)

Answer 17

Oh stop it :)