Question

establish Rs= R1+R2+R3

Answer 1

See
V=IR .......... (ohm's law)
In series combination,
V(voltage) is varying and I(current) is same
So,
V=V1+V2+V3
=>IR =IR1+IR2+IR3
=>R = R1+R2+R3 (taking I as common both the side)

(hence proved)


Hope its helpful

Answer 2

Your answer :

V=IR .......... (ohm's law)

In series combination,

V(voltage) is varying and I(current) is same

So,

V=V1+V2+V3

=>IR =IR1+IR2+IR3

=>R = R1+R2+R3 (taking I as common both the side)