Check my work please? Circuit analysis, resistors in parallel, help

[nchin]

Can someone check my work for me please? I'm pretty sure i made a mistake with the sign convention but I'm not sure which sources are supposed to be negative. help!

Problem:
http://imageshack.us/a/img201/339/circuitzz.png

My solution:
http://imageshack.us/a/img191/8049/circuitz.png

The top half is me solving the left side the circuit and the bottom half is the right side of the circuit.

 

[CWatters]

The basic calculations/magnitude look fine to me. However the passive convention says that the power of the sources would be negative. So for example the power of the 60V source is -0.6W.

Examples..
http://circuits.solved-problems.com/456/problem-1-15-power-independent-sources/

 

[nchin]

so if the power of the 60v source is -0.6, does that mean the power in resistor 1 is -0.1 and the power in resisor 2 is -0.5? since power supplied = power dissipated?? (-0.6 = -0.1 + (-0.5))?

 

[nchin]

ok nvm i figured it out,, but am i solving r3 and r4 correctly?

 

[CWatters]

so if the power of the 60v source is -0.6, does that mean the power in resistor 1 is -0.1 and the power in resisor 2 is -0.5? since power supplied = power dissipated?? (-0.6 = -0.1 + (-0.5))?

No the power dissipated in the resistors is +ve. You write something like..

Power in source + Power in load = 0

-0.6 + 0.1 + 0.5 = 0

 

[CWatters]

I threw away the scrap paper I used yesterday but yes I got the same power disipation as you for R3 and 4.