Question

two resistance are connected in series and parallel the effective resistance becomes 18 ohm and ohm 4 Ohm​

Answer 1

Explanation :-

let R1 and R2 are two resistance .

in series combination .

=> R1 + R2 = 18 ohm -----------1

in parallel combination.

=> R eq = (R1 × R2)/R1 + R2 = 4 ohm

=> (R1 × R2)/18 = 4 ohm

=>(R1 × R2) = 72

Now using formulas.

=> ( R1 - R2 )² = (R1 + R2)² - 4 R1 × R2

so , R1 - R2 = 6 ---------2

now , using 1 And 2 .

=> R1 = 12 and R2 = 6 .