Two known resistances of \( R\,\Omega \) and \( 2R\,\Omega \) and one unknown resistance \( x\,\Omega \) are connected in a circuit as shown in the figure. If the equivalent resistance between points \( A \) and \( B \) in the circuit is \( x\,\Omega \), then the value of \( x \) is _______ \( \Omega \).
