I was taught thevnins therom using the the short circuit method.

Vth = Isc*Rth

Take a simply voltage divider where R1 and R2 = 10k

The point of interest of A and B commonly called would be across R2.

So i was taught or at least i think i was to do the following.

Find ISC as if points A and B were shorted.

So in this case using a 15V supply i would have

15V / 10k = 1.5 mA is ISC

Then Vth would be what is the voltage at point A with A and B open, well, that in a voltage divider that is just the supply voltage of 15V.

So vth = 15V and Isc = 1.5 mA

So rth = 15V/1.5mA = 10k of course

So the eq circuit is a 15V supply with a 10 k resistor.

What did i do wrong here?