Exercise question about Thévenin theorem
R1 ia shorted with the conducting wire in place of V1 so the parallel equivalent resistance is 0 ohm (For two resistances in parallel, equivalent resistance is $R=\ frac{R1×R2}{R1+R2}$, If any resistance is zero, equivalent resisatnce is also zero). R3 has been open circuited correctly therefore the thevenin resistance is R2 and not R1