Let $\left(x_0, y_0\right)$ be the solution of the following equations $(2 x)^{\ln 2}=(3 y)^{\ln 3}$,…
Let $\left(x_0, y_0\right)$ be the solution of the following equations $(2 x)^{\ln 2}=(3 y)^{\ln 3}$, $3^{\ln x}=2^{\ln y}$, then $x_0$ is equal to
- $\frac{1}{6}$
- $\frac{1}{3}$
- $\frac{1}{2}$
- 6
Solution
Taking ln on both sides,
$\ln 2 \cdot \ln (2 x)=\ln 3(\ln 3 y)$
$\begin{array}{ll}
\Rightarrow & \ln 2\{\ln 2+\ln x\} \\
& =\ln 3\{\ln 3+\ln y\} \\
\text { and } & \ln x \cdot \ln 3=\ln y \ln 2 \\
& \ln y=\frac{\ln x \cdot \ln 3}{\ln 2}
\end{array}$
From Eqs. (i) and (ii), we get
$\begin{aligned}
& \ln 2\{\ln 2+\ln x\} \\
&=\ln 3 \cdot\left\{\ln 3+\frac{\ln x \cdot \ln 3}{\ln 2}\right\} \\
& \Rightarrow(\ln 2)^2+\ln 2 \cdot \ln x \\
&=(\ln 3)^2+\frac{(\ln 3)^2}{(\ln 2)} \cdot \ln x \\
& \Rightarrow \ln x\left\{\frac{(\ln 3)^2}{\ln 2}-\ln 2\right\} \\
&=(\ln 2)^2-(\ln 3)^2
\end{aligned}$
$\begin{aligned}
& \Rightarrow \ln x=-\ln 2=\ln 2^{-1} \\
& \therefore x=\frac{1}{2}
\end{aligned}$
Asked in: JEE Advanced 2011 (Paper 1)
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