Why is one transistor in active and the other in triode?
When facing these kind of exercises your should first of all write down the typical MOS operating region conditions. A good, simple (and very approximated) start could be the following:

Is M2 ON? 

3V - V1 > Vth

Assuming it is conducting, then V1 should have a maximum value of 2.6V

Is M2 working in saturation?

3V - V1 > 3V - V1 - Vth
3V > 3V - Vth

Yes, M2 is working in SATURATION

Is M1 ON? 

3V > Vth

Yes, M1 is ON 

Is M1 working in saturation?

V1 > 3V - Vth

V1 > 2.6 V

In the "worst case" (V1 = 2.6V) M1 would be ALMOST in saturation. But here the key is the Length of M1 and M2. As you can observe, L1 is smaller than L2. Lets now suppose both M1 and M2 are working in saturation and obtain the value of V1 using the drain-source current equation without taking into account the body effect.

Ids1 = K'/2 * (2*W/L2) * (3 - 0.4)^2

Ids2 = K'/2 * (W/L2) * (3 - V1 - 0.4)^2

Ids1 = Ids2

Solving this equation we obtain V1 = 6.27 V and -1V, which are not possible values. Thus both transistors cannot be working in saturation, and we can conclude saying that:

M2 is working in saturation and M1 is working in ohmic region