Question

When two resistance are connected in series ,they have vale 25 ohm and connected in parallel 4 ohm .Find the value of each resistance?

Answer 1

Answer:

let the value of both resistance be x and y.

if they are in series,then

x+y= 25------(1)

if they are in parallel, then,

xy/(x+y)=4

xy/25=4. { using eq.(1)}

xy = 100

x(25-x)=100. {using eq.(1)}

25x-x2=100

x2-25x+100=0

x2-20x-5x+100=0

x(x-20)-5(x-20)=0

(x-5)(x-20)=0

x=5 and 20

thus ,if x=5 then y= 20

if x=20 then y= 5

I hope it would help you.