Question

What is the value of x in the solution of this system?
-3x-y+2z=7
2y+z=-5
3x+6y=-21

A) -4
B) -2
C) 1
D) 3

Answer 1

have you tried ? or no clue ?

Answer 2

Im not really sure how to do this? Can you explain it to me?

Answer 3

you can use substitution or elimination

Answer 4

for example .. if we go for substitution .. we can take the first equation and find what "3x" is :

-3x-y+2z=7
then we get
3x=2z-y-7

we do so since in the third equation we have 3x.. so we may replace it with what we found:
3x+6y=-21
plug in here 3x
and get:
2z-y-7+6y=-21

then you find here some information about z or y and plug it into the second equation..

Answer 5

Im still a little confused what is the answer? maybe i can work my way backwards after i have it

Answer 6

I would start by finding what z is equal to...using the second equation you can easily come to that answer.

After that, take what you found for z and plug that into equation one and either solve for x or y (doesn't matter). after you have found that answer(either x or y) plug that into equation 3.

Does that make sense?

Answer 7

ah yes i understand now thanks everyone