Question

need help with solving systems of equations
4x+2y-6z=-38
5x-4y+z=-18
x+3y+7z=38

Answer 1

so far I tried to combine all three and got 10x+y+2z=-18
now I'm not sure what to do

Answer 2

x = 38 - 3y - 7z (from 3rd equation)
sub that into equation 2
5x-4y+z=-18

Answer 3

you need to use the elimination method

Answer 4

or substitution

Answer 5

ok so substituting the third equation into the secon i'll get
5(38-3y-7z)-4y+z=-18

Answer 6

190-15y-35z-4y+z=-18

Answer 7

5x - 4y + z =-18
5(38 - 3y - 7z) -4y + z = -18
will give you an answer purely in terms of y and z
put in terms of z=....

sub that answer into eqn 1 along with your answerr from eqn 3 (x=...)
wil give u an exact answer for y

Answer 8

one sec

Answer 9

ok right now I got 34z=208-19y

Answer 10

cool, so z=(208-19y)/34

Answer 11

ok but how do I divide that not knowing what y is?

Answer 12

cool, so sub x = 38 - 3y - 7z into eqn 1
expand and add like terms
then sub z=(208-19y)/34
you'll be left with y = answer

Answer 13

I got z=(-190+10y)/34
and from equ.2
z=(208-19y)/34

Answer 14

im confused.

Answer 15

yep, sub in x=...
gives you: 10y + 34z = 190
and sub in z=...
gives you 10y + 34((208-19y)/34) = 190
so 34/34 = 1/1
so left with: 10y + 208-19y = 190
= -9y = -18
y = -18/-9 = 2
therefore y = 2

Answer 16

ooooooooooooooooo i think I got it

Answer 17

cools
now use z=(208-19y)/34 to find z
and x = 38 - 3y - 7z to find x

done ;D

Answer 18

slaters, good luck

Answer 19

x=-3,
y=2,
and z=5

Answer 20

Thanks so much!!!!!!!!!!!!!!!!

Answer 21

perfect, props hey ;D