Designing different amplifiers with known gain

[CSOleson]

Homework Statement

I am designing three amplifiers:
1. is an noninverting amplifier with G=200
2. is an inverting amplifier with G=-50
3. is a summing amplifier with V(out)--50V(in1)-3V(in2)-15(Vin3)

all problems i(outmax)=2mA

So far the only problem I have figured anything about is the noninverting amplifier. I still cannot seem to find a way to relate Vin and Vout with what I know. I got as far as finding G=i(out)R(2)
Where do I go from here?

Homework Equations

1. i(out)=i(2)=V(out)/(R(1)+R(2))

The Attempt at a Solution

The second two problems I don't know where to start with them.

 

[berkeman]

Homework Statement

I am designing three amplifiers:
1. is an noninverting amplifier with G=200
2. is an inverting amplifier with G=-50
3. is a summing amplifier with V(out)--50V(in1)-3V(in2)-15(Vin3)

all problems i(outmax)=2mA

So far the only problem I have figured anything about is the noninverting amplifier. I still cannot seem to find a way to relate Vin and Vout with what I know. I got as far as finding G=i(out)R(2)
Where do I go from here?

Homework Equations

1. i(out)=i(2)=V(out)/(R(1)+R(2))

The Attempt at a Solution

The second two problems I don't know where to start with them.

What are the two basic properties of opamps that you use to figure out the gain of different configurations? One property has to do with the current that flows into the + and - terminals, and the other property has to do with the voltage difference between the + and - input when the opamp has negative feedback connected...

 

[berkeman]

And here is a basic tutorial: http://en.wikipedia.org/wiki/Opamps