Question

f you were to use the substitution method to solve the following system, choose the new system of equations that would result if x was isolated in the second equation.

3x + y + 2z = 1
x + 2y - z = -8
3x - y - 3z = 18

Answer 1

@terenzreignz

Answer 2

@terenzreignz

Answer 3

So, in the second equation, as instructed, isolate x
IE rearrange it so that x stands alone in one side of the equation.

Answer 4

a. 7y - z = 25
5y - 6z = 42
b. -5x - 5z = -10
6x - z = 19
c. 7x + 3z = -10
0x - 5z = 19
d. -5y + 5z = 25
-7y = 42

Answer 5

x=-8-2y+z

Answer 6

\[x=-8-2y+z\]

Answer 7

@Turner

Answer 8

That's right. Now replace the x in both the first and third equations by this new expression.

Answer 9

alright one sec

Answer 10

\[3(-8-2y+2)+2z=1\]

Answer 11

\[3(-8-2y+z)-y-3z=18\]

Answer 12

the 2 should be a z in the ( )

Answer 13

So, simplify this.
Do the same with the third equation.

Answer 14

ok one sec

Answer 15

-24-6y+5z=1

Answer 16

-24-5y+z=18

Answer 17

is that correct

Answer 18

Check if you're using the correct equation!
3x + y + 2z = 1
Now, do it again, replace the x.

Answer 19

ok

Answer 20

x = z - 2y - 8

Answer 21

so it should look like this -24-6y+3z+y+2z=1

Answer 22

-24-7y+5z=1

Answer 23

-6y + y = 7y?
recheck.

Answer 24

-24-5y+5z=1

Answer 25

Yes. But bring that -24 over to the other side.

Answer 26

-5y+5z=25

Answer 27

I guess at this point we can stop. Only one of the choices has this equation.
You can verify that doing the same substitution to the third equation will add up.

Answer 28

ok i have one more

Answer 29

If you were to use the elimination method to solve the following system, choose the new system of equations that would result after the variable z is eliminated in the first and second equations, then the second and third equations.

x + y - 3z = -8
2x + 2y + z = 12
3x + y - z = -2