Question

Urgent help needed :/

Solve the following system of equations:

4x − 2y − z = −5
x − 3y + 2z = 3
3x + y − 2z = −5

Answer 1

You can solve these by the method of elimination

HinT start by adding equations 2 and 3
This will eliminate z.

Answer 2

The middle and lower one?

Answer 3

yes

Answer 4

okay

Answer 5

Am I combining them?

Answer 6

yes add the x terms , add the y terms -2z + 2z = 0 so z disappears. and add 3 and -5.

Answer 7

okay

Answer 8

4x-2y=-2

Answer 9

Correct
Now we need to eliminate z using 2 different equations

You could multiply the first equation by 2 then add it to equation 3.

Answer 10

Im confused, didn't we already eliminate z?

Answer 11

Sorry multiply fisr equation by -2

Answer 12

Yes but we need another equation in x and y so we have to eliminate z frm another 2 equations.

Answer 13

so * no 1 by -2:-

-8x + 4y + 2z = 10
3x + y - 2z = -5 ADD

Answer 14

okay

Answer 15

-5x+5y=5

Answer 16

OK

Now we can simplify that one to make our work easier

How can we do that?

Answer 17

Move a variable to another side?

Answer 18

No
Just divide through by 5 giving us

-x + y = 1

Answer 19

now we have 2 equations in x and y

4x - 2y = -2
-x + y = 1

Answer 20

Now i realised - we can also divide the first equation by 2 giving

2x - y = 1
-x + y = 1

Answer 21

* typo

2x - y = -1
-x + y = 1

Answer 22

okay

Answer 23

now add these 2

Answer 24

x=0?

Answer 25

correct

Answer 26

now plug in x = 0
0 + y = 1
y = 1

Answer 27

okay

Answer 28

Now you can easily find z by plugging in x = 0 and y = 1 into one of the original equations

Answer 29

okay

Answer 30

-3

Answer 31

I got 3

Answer 32

4(0) - 2(1) - z = -5
-2 - z = -5
-z = -3
z = 3

Answer 33

Its worth checking if the answer is correct by plugging in values of x y and z into another one of the equations.

Answer 34

try the last one

3(0) + 1 - 2(3) = 1 - 6 = -5 - this checks out

Answer 35

Hope this has helped

gtg right now.

Answer 36

Thank you for the help!

Yeah, sorry I had to go too, i was running late for a live lesson by the time I finished :/ @welshfella