Node Method Problem: Identifying Errors

[LongApple]

Homework Statement

Homework Equations

V=IR

The Attempt at a Solution

I believe my a1 and a2 are correct.

But my b1 is definitely wrong. Even if I carry out the above subtraction for the v1 part (which gives you b1) I will not have somethign as simple as R2 + R3 on the numerator

[/B]

Where would be some starting places to pinpoint the error?

 

[LongApple]

I'll try putting in dark blue.

Is this any easier to read?

I cannot change some of the below because some of it is pasted images

 

[haruspex]

You're not supposed to post working as handwritten images. It's hard to read and hard to reference when making comments.
Given the answer for a1, please post your working to obtain b1 in typed text - preferably LaTeX, or using subscripts, but that's not essential.

 

[rude man]

This is a good time to apply the superposition principle.