Đáp án:
\({R_1} = {R_2}\)
Giải thích các bước giải:
\(\begin{array}{l}
{R_{nt}} = {R_1} + {R_2}\\
{R_{//}} = \dfrac{{{R_1}{R_2}}}{{{R_1} + {R_2}}}\\
\dfrac{{{P_{//}}}}{{{P_{nt}}}} = \dfrac{{\dfrac{{{U^2}}}{{{R_{//}}}}}}{{\dfrac{{{U^2}}}{{{R_{nt}}}}}} = \dfrac{{{R_{nt}}}}{{{R_{//}}}}\\
\Rightarrow 4 = \dfrac{{{R_1} + {R_2}}}{{\dfrac{{{R_1}{R_2}}}{{{R_1} + {R_2}}}}}\\
\Rightarrow {({R_1} + {R_2})^2} = 4{R_1}{R_2}\\
\Rightarrow R_1^2 + R_2^2 + 2{R_1}{R_2} = 4{R_1}{R_2}\\
\Rightarrow R_1^2 + R_2^2 - 2{R_1}{R_2} = 0\\
\Rightarrow {({R_1} - {R_2})^2} = 0\\
\Rightarrow {R_1} - {R_2} = 0\\
\Rightarrow {R_1} = {R_2}
\end{array}\)
