\({R_P} = \frac{{{R_1}{R_2}}}{{{R_1} + {R_2}}}\)
\(==>\) \(\frac{{{R_S}}}{{{R_P}}} = \frac{{{{({R_1} + {R_2})}^2}}}{{{R_1}{R_2}}} = n\)\(==>\)\(\frac{{{R_1} + {R_2}}}{{\sqrt {{R_1}{R_2}} }} = \sqrt n \)
\(==>\)\(\frac{{\sqrt {R_1^2} }}{{\sqrt {{R_1}{R_2}} }} + \frac{{\sqrt {R_2^2} }}{{\sqrt {{R_1}{R_2}} }} = \sqrt n \)
\(==>\) \(\sqrt {\frac{{{R_1}}}{{{R_2}}}} + \sqrt {\frac{{{R_2}}}{{{R_1}}}} = \sqrt n \)