Question

In the circuit shown in Figure, calculate the value of $x$ if equivalent resistance between the points A and B is $4\Omega$

Answer 1

$\frac{1}{R_{eq}}=\frac{1}{12}+\frac{1}{5+x}$

$\frac{1}{4}=\frac{5+x+12}{12(5+x)}$

or, $3(5+x)=17+x$

$15+3x=17+x$

$2x=2$

$x=1\Omega$