Question

teach me on how to get the value of this 3 variables
I have slight knowledge about this but i can't get the value with these systems of linear equations

help me please

Please answer clearly and explain the solution clearly and easy to understand. Thanks!
(guaranteed medal for a good answer)

Answer 1

2x+3y-z=4
3x-4y+4z=11
5x-2y+z=5

Answer 2

this is what i made:

2x+3y-z=4 (1)
3x-4y+4z=11 (2)
5x-2y+z=5 (3)
I multiplied eq. 1 by 4
(2x+3y-z=4)4
then added it to eq.2
8x+12y-4z=16 (1)
3x-4y+4z=11 (2)
=11x+8y=27 (4)

then i multiplied eq.3 to -4 and added to eq.2
(5x-2y +z=5)4
then added it to eq.2
3x-4y+4z=11 eq.2
-20x+8y-4z=-20 eq. 3
=-17+4y=9 (5)

then i multiplied (5) to -2
34x-8y=-18 (5)

then i added it to (4)
11x+8y=27
34x-8y=-18
= 45x=9

x=9/45

i know my answer is wrong, but where did i go wrong?

Answer 3

why do you say your answer is wrong?

Answer 4

because i got zero in my quiz?

Answer 5

here is the answer but i can't understand it
http://openstudy.com/groups/mathematics#/groups/mathematics/updates/4e2109660b8ba00f8f002261

Answer 6

8x+12y-4z=16
3x-4y+4z=11
--------------- +
11x + 8 y = 27

3x-4y+4z = 11
20x-8y+4z=20
--------------- -
-17x+4y=-9

11x+8y = 27
-34x+8y=-18
-------------- -
45x = 45
x = 1

Your approach is correct, but I think you may have made a mistake with the + or - sign

Answer 7

Check your arithmetic for equation (5)

Answer 8

then i multiplied eq.3 to -4 and added to eq.2
(5x-2y +z=5)4
then added it to eq.2
3x-4y+4z=11 eq.2
-20x+8y-4z=-20 eq. 3
=-17+4y=9 (5)

it should be =-17+4y=-9 (5)
I've replied this in http://openstudy.com/groups/mathematics#/groups/mathematics/updates/4e2109660b8ba00f8f002261