Why they have taken -4(x-y) for system 2 why not 4(x-y) in example 37

# Doubt from nodal capacitive analysis

Because in the first system we have assumed that the left plate of 4uF capacitor has positive charge so right plate must have negative charge which we take in second system.

(This problem arises when the same capacitor is present in two nodal equations.)

Ok thank you

And by the way, in the equation of second system last term should be 2(y-4)

Ya i got it

ya sorry

In question no 6 how they are taking C3 and C4=4microfarad when it is given they are 6 microfarad. I am confused in their solution.

Please help anyone