Question

please help me solve 1 problem with 3 variables and 3 equations.
11.) 2x+3y+2z=1
x+4y-z=7
3x+y+3z=-2
elimination please. what do I do first??

Answer 1

Substitution would be easier... do you have to use elimination?

to eliminate z in the first equation:
2x+3y+2z=1
+2(x+4y-z=7)
---------------

Answer 2

no we don't have to use elimination I find it easier to understand though. it says substitution orr elimination.. please explain what u put above?

Answer 3

I got 4x+11y=8 using it your way sir? @argent0smith ??

Answer 4

I'd recommend substition then (it's easier with 3 equations. 2 equations elimination is easier). You did that right (except 8 should be 15), but elimination is...ugh with three.

Solve this equation for x =....

x+4y-z=7

Answer 5

im lost so badly. ???? please help me with www.vyew.com and post link on here

Answer 6

Just rearrange this equation until it looks like x=

x+4y-z=7

start by subtracting 4y on both sides

Answer 7

4x+11y=15 -> 11y+4x=15
x+4y-z=7-> 4y-z=7 is that right?

Answer 8

im LOSTtttt??????

Answer 9

Just use x+4y-z=7, we aren't using the other equation.

subtracting 4y on both sides gives

x-z=7 - 4y

now add z to both sides

Answer 10

it all depends on your preference, i find elimination to be easier even for 3 equations

Answer 11

now what /: elimination I understand better I don't understand his method at allll

Answer 12

either way you have to eliminate a variable to turn it into a system of 2 equations, then solve that system

Answer 13

Okay then go with what we have above: 4x+11y=15. Leave that alone for now, don't use it.

now do this one:
3(x+4y-z=7)
-3x+y+3z=-2
------------------

Answer 14

(that's the middle and last equations)

Answer 15

oops,
3(x+4y-z=7)
-(3x+y+3z=-2)
------------------

Answer 16

That'll actually allow us to solve for y...

Answer 17

im losttt @agent0smith please help me the elimination way

Answer 18

That is the elimination way.

Answer 19

I got this 3x+4y-z=7
-3x+y+3z=2

= 5y-2z=9 Right?????

Answer 20

3(x+4y-z=7)
-(3x+y+3z=-2)
------------------

the things outside the brackets apply to EVERY term inside the brackets. Not just the first term.

Answer 21

12y+6z=7 ??

Answer 22

actually we need to add them, to eliminate z, not x

3(x+4y-z=7)
+(3x+y+3z=-2)
-----------------

first distribute the 3 outside the brackets

3x+12y-3z=21 (multiply all by 3)
+(3x+y+3z=-2)
-----------------

Answer 23

I did multiply everything by 3 and I added what I got and it come to 12y+6z=7

Answer 24

Use the correction above.

3x+12y-3z=21
+(3x+y+3z=-2)

Answer 25

I did already... U keep repeating urself but im still Lost..sir?

Answer 26

12y+6z=7 is not correct, for the above

Answer 27

I added and multiplied by 3 what u put and got 12x+ 37y-6z=19 for a total after I multiplied and added

Answer 28

That's not right. Add together all the terms that are lined up vertically.

3x +12y -3z = 21
+ 3x +y +3z = -2

Answer 29

6x+13y=19 ? and howd u get those 2 equations?? still lost )":

Answer 30

We got them from above, scroll way back up.

And 6x+13y=19 is correct. Now you need to go back to this one from earlier... 4x+11y=15

and solve them together:

6x+13y=19
4x+11y=15

Answer 31

my laptop is jetlaging I got 10x+24y=34

Answer 32

now what??????

Answer 33

We can't just add them together. You need to solve them using elimination. We can eliminate x like so

2(6x+13y=19)
-3(4x+11y=15)
--------------

don't forget to apply the numbers outside to everything in the brackets

Answer 34

y=1 ????? /:

Answer 35

Yes. Now use any equation to solve for x, we know what y is... like this one 4x+11y=15

Answer 36

thanks I got it from here. im still lost until I get to here tho would u help me set up 12. just tell me what to do??? like put it step by step please??

Answer 37

12.) x-2y+3z=-7
4x+5y+z=4
-x+y-2z=5

Answer 38

Start with the first and last, since you can eliminate x easily

add them together:
x-2y+3z=-7
-x+y-2z=5


then add the middle and last, like so, to eliminate x

4x+5y+z=4
+4(-x+y-2z=5)

then, you'll have two equations from those with only y and z, which you can solve together.

Answer 39

I still have x on one of them? I got -y+ -z=12 and I got -3x+6y-z=9

Answer 40

Check your work, 4x minus 4x is zero.

-y+ -z=12 is not correct... z should be positive, -7 plus 5 is not 12.

Answer 41

ok I redid it and got.. 6y-z=9
+ -y+-z=12

Answer 42

The first, adding them:
x-2y+3z=-7
+ -x+y-2z=5
-----------
-y + z = -2 <=== that is what you should get

Answer 43

now what?

Answer 44

Have you done this one correctly yet? the -3x+6y-z=9 you posted isn't right

(adding them)
4x+5y+z=4
+4(-x+y-2z=5)

Answer 45

yeah I got -y+z=-2 but idk how u got that??

Answer 46

how i got what?

Answer 47

how u got -y+z=-2

Answer 48

I got 6y-z=9 im lost? is that right.??

Answer 49

I got it by adding the two together. That isn't right.

4x+5y+z=4
+4(-x+y-2z=5)

4x+5y+z=4
+ -4x+4y-8z=40 (after multiplying all of it by 4)

Answer 50

9y+-7z=44

Answer 51

Yes

now solve these two (you can't just add them as is, use elimination)

-y + z = -2
9y-7z=44