Solving 0th-Order Circuit Equations with Two Variables

[pat666]

Homework Statement

see attached

Homework Equations

The Attempt at a Solution

$$0=(v_1-128)/5-V_1/60-(v_2-V_1)/4$$
$$0=(v_2-v_1)/4-v_2/80-(v_2-320)/10$$
I obviously know what the answer should be from multisim but its not coming out. I've tried multiple combinations of this mainly just changing -s to +s because I can never get the current direction right for some reson.

Thanks

edit: the covered up resistor is a 10ohm

 

[berkeman]

Homework Statement

see attached

Homework Equations

The Attempt at a Solution

$$0=(v_1-128)/5-V_1/60-(v_2-V_1)/4$$
$$0=(v_2-v_1)/4-v_2/80-(v_2-320)/10$$
I obviously know what the answer should be from multisim but its not coming out. I've tried multiple combinations of this mainly just changing -s to +s because I can never get the current direction right for some reson.

Thanks

edit: the covered up resistor is a 10ohm

Yeah, your signs are kind of strange. I just write the sum of the currents out of a node is equal to zero. Don't do subtractions or whatever you are doing.

So your first equation should be:

(v1-V1)/5 + v1/60 + (v1-v2)/4 = 0

Write out both equations using this form, and see if it all solves up better...

 

[pat666]

Yeah, I had an epiphany last night and started getting these right:)
(v1-128)/5 + v1/60 + (v1-v2)/4 = 0
(v2-V1)/4+v2/80+(v2-320)/10=0

v1=162
v2=320

 

[berkeman]

Yeah, I had an epiphany last night and started getting these right:)
(v1-128)/5 + v1/60 + (v1-v2)/4 = 0
(v2-V1)/4+v2/80+(v2-320)/10=0

v1=162
v2=320

v2 looks wrong. V2 = 320V is the right side source, so v2 has to be less than 320V...

 

[pat666]

oops that's a typo v2 cane out as 200V, I put it in Mathematica and it matched multisim so i assumed that I was correct.