# Find Vx using node voltage method

1. Mar 20, 2017

### Samira

is= 1.2 mA

i submitted my solution but it was wrong,can someone please explain why?

/* i just wanted to check if my solution is correct so i don't lose marks on my homework
did i do any mistakes ?
my solution:

Last edited: Mar 20, 2017
2. Mar 20, 2017

### CWatters

I haven't gone through all your working but check the polarity of the 30V source and the first term in the KCL equation.

3. Mar 20, 2017

### Staff: Mentor

Hi Samira,

Welcome to Physics Forums!

In future be sure to use the homework formatting template that is provided in the edit window when a new thread is started here in a homework forum. It is one of the rules of the forums and you will find your posts deleted if it is not used.

4. Mar 20, 2017

### Samira

5. Mar 21, 2017

### CWatters

I still think the first term should be (Vx - (-30)) / 5

For example to be consistent with the third term (Vx-(+80))/1

6. Mar 21, 2017

### Staff: Mentor

Argh! You're right! I missed the reversed polarity on the 30 V supply Good catch.

@Samira : The first term in your node equation needs to be fixed. It should be $\frac{V_x + 30}{5}$ .

7. Mar 21, 2017

### Samira

i'm sorry i did not see your answer last night , i thought i only got one.
thank you !