Divided by 8 kilo ohms and of course we have the third current which you
know is zero coming out of the inverting input of the op amp.
I'm going to put it in there for
completeness and the some of those currents is equal to zero.
So now we have an equation that has V out is the only unknown in the equation.
If we solve for v out, We end
up with a v out which is equal to -30 volts.
So now that's one of our variables that we want to determine in this problem.
The other one is I out,
we want to find the current through the a kilo ohm resistor and
we know what that's going to be because we're already investigated that.
But as it's described and defined in this problem I out is in the opposite
direction of the current that we were summing into node one.
So I out, if we're going to find that current, we know I out,
it's going to be equal to the voltage at this point, node one,
which is -2 volts minus this voltage which is V out.
So it's -2- V out / 8 kilo ohms.
And that will give us I out.
We know what V out is, it's -30 volts.