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Mathematics 8 Online
OpenStudy (anonymous):

What is the solution to the system? *PICTURES ATTACHED*

OpenStudy (anonymous):

OpenStudy (anonymous):

(-4, 0, 12) (-3, 5, 6) (0, -2, -12) (2, 1, -3)

OpenStudy (anonymous):

@yb1996 HELP PLEASE:(

jimthompson5910 (jim_thompson5910):

First isolate z in the third equation. What do you get?

OpenStudy (anonymous):

um i would isolate it by multiplying the first equation by -2... correct?

jimthompson5910 (jim_thompson5910):

nope, just solve for z in the third equation

jimthompson5910 (jim_thompson5910):

focus on just the third equation for now

OpenStudy (anonymous):

ok one sec

OpenStudy (anonymous):

idk how to do this:(

OpenStudy (anonymous):

@jim_thompson5910

jimthompson5910 (jim_thompson5910):

6x + z = -12

jimthompson5910 (jim_thompson5910):

think of 6x + z as z + 6x

jimthompson5910 (jim_thompson5910):

you must do something to both sides to move that 6x over

OpenStudy (anonymous):

would i subtract the six on both sides or divide...something like that?

jimthompson5910 (jim_thompson5910):

6x

jimthompson5910 (jim_thompson5910):

subtract 6x from both sides

OpenStudy (anonymous):

so now i have z = -12 - 6x correct?

jimthompson5910 (jim_thompson5910):

yes

jimthompson5910 (jim_thompson5910):

now that you know z = -12 - 6x, you can plug this into the other copies of 'z' in the other equations

jimthompson5910 (jim_thompson5910):

for example, in equation 1 x + 3y - z = 6 x + 3y - ( z ) = 6 x + 3y - ( -12 - 6x ) = 6 ... replace every copy of z with -12 - 6x x + 3y + 12 + 6x = 6 7x + 3y + 12 = 6 7x + 3y = 6 - 12 7x + 3y = -6 Hopefully you understand what is going on with each step

OpenStudy (anonymous):

i kinda understand but I am not getting any closer to finding my answer...

jimthompson5910 (jim_thompson5910):

we're getting there (eventually)

jimthompson5910 (jim_thompson5910):

what do you get if you plug z = -12 - 6x into equation 2 ?

OpenStudy (anonymous):

i give up thanks for the help though.

jimthompson5910 (jim_thompson5910):

come on, give it a shot at least

jimthompson5910 (jim_thompson5910):

4x - 2y + 2z = -10 replace z with -12 - 6x and simplify

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