Question

What is the solution of the system of equations?
-3x-4y-3z=-7
2x-6y+2z=3
5x-2y+5z=9
Please help me I'm really confused!

Answer 1

multiply by (-) the 2nd eq
then plus 1st eq
so you can find y

Answer 2

what? i'm still confused, multiply what in the second equation by (-)? @amoodarya

Answer 3

hint the system of equations has no answer

Answer 4

-3x-4y-3z=-7
-2x+6y-2z=-3 *(-1)
5x-2y+5z=9

Answer 5

sum of 1st and 2nd
-3x-4y-3z=-7
-2x+6y-2z=-3
is -5x+2y-5z=-10

Answer 6

now compare with 3rd eq

Answer 7

wait so there is no solution? then why do you have to compare them? @amoodarya

Answer 8

-5x+2y-5z=-10
5x-2y+5z=9
it is impossible
try to compare them

Answer 9

sum of them
is
5x-2y+5z=9
-5x+2y-5z=-10

0x+0y+0z=9-10
so 0=-1
the system has no answer

Answer 10

oh okay I get it. thanks! can you help me with another one?

Answer 11

@amoodarya

Answer 12

yes

Answer 13

Solve the system by elimination.
-2x+2y+3z=0
-2x-y+z=-3
2x+3y+3z=5
I need help like step by step because I don't understand how to do this one at all @amoodarya

Answer 14

first name them
(1) -2x+2y+3z=0
(2) -2x-y+z=-3
(3) 2x+3y+3z=5

Answer 15

no calculate 1+3
and 2+3

Answer 16

so the first equation plus the second equation and the second equation plus the third equation?

Answer 17

now calculate eq 1+eq 3
and eq 2+eq 3
because "x" omited

Answer 18

you must have
5y+6z=5
4y+4z=2
ok ?

Answer 19

Okay @amoodarya

Answer 20

sorry
5y+6z=5
2y+4z=2

now
multiply the 1st by -4
multiply the 2nd by +6
then sum of them

Answer 21

then you must have -8y=-8
ok ?

Answer 22

right ok @amoodarya

Answer 23

wait how did you get -8y=-8?

Answer 24

maybe @hero can help?

Answer 25

and now
what is problem?

Answer 26

5y+6z=5
2y+4z=2

-4 *(5y+6z=5)
+6* (2y+4z=2)

-20y-24z=-20
12y+24z=12
sum of them
-8y=-8
so y=1
canyou go on ?

Answer 27

then put y=1
you must have z=0
and then put y=1 and z=0 you must have x=1

Answer 28

Briana_Brooke are u there ?

Answer 29

oh okay I see how you got it now is that it or is there more to do? @amoodarya

Answer 30

nothing more

Answer 31

okay thanks!

Answer 32

@Briana_Brooke

Answer 33

This is the original system:

-3x-4y-3z=-7
2x-6y+2z=3
5x-2y+5z=9

Answer 34

Notice that the first and third terms in each equation are the same.

Answer 35

Oh...I see...nevermind

Answer 36

I didn't realize you guys went over two problems.

Answer 37

Good job @amoodarya