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JEE MainMathematics/ ModerateLogarithm

Let (x0,y0)\left( x_{0},y_{0} \right) be the solution of the following
equations

(2x)ln2=(3y)ln3(2x)^{\mathcal{l}n2} = (3y)^{\mathcal{l}n3}
3lnx=2lny3^{\mathcal{l}nx} = 2^{\mathcal{l}ny}
Then
x0x_{0}is

Show answer and solution
(2x)ln2=(3y)ln3(2x)^{\mathcal{l}n2} = (3y)^{\mathcal{l}n3}
⇒ln2 ln(2x)=ln3 ln(3y)=ln3 (ln3+lny)\Rightarrow \mathcal{l}n2\ \mathcal{l}n(2x)\mathcal{= l}n3\ \mathcal{l}n(3y)\mathcal{= l}n3\ (\mathcal{l}n3 + \mathcal{l}ny)....(1)
Also
3lnx=2lny3^{\mathcal{l}nx} = 2^{\mathcal{l}ny}
⇒lnxln3=lny ln2\Rightarrow \mathcal{l}n{x\mathcal{l}n3}\mathcal{= l}ny\ \mathcal{l}n2....(2)
By (1)

⇒ln2 ln(2x)=ln3(ln3+lny)\Rightarrow \mathcal{l}n2\ \mathcal{l}n(2x) = \mathcal{l}n3(\mathcal{l}n3 + \mathcal{l}ny)
⇒ln2⋅ln(2x)=ln3{ln3+ln×ln3ln2}\Rightarrow \mathcal{l}n2 \cdot \mathcal{l}n(2x) = \mathcal{l}n3\{\mathcal{l}n3 + \frac{\mathcal{l}n \times \mathcal{l}n3}{\mathcal{l}n2}\}
⇒ln22 ln2x=ln23(ln2+lnx)\Rightarrow \mathcal{l}n^{2}2\ \mathcal{l}n2x = {\mathcal{l}n}^{2}3(\mathcal{l}n2 + \mathcal{l}nx)
⇒(ln22−ln23)(ln2x)=0\Rightarrow ({\mathcal{l}n}^{2}2 - {\mathcal{l}n}^{2}3)(\mathcal{l}n2x) = 0
⇒ln2x=0⇒x=12\Rightarrow \mathcal{l}n2x = 0 \Rightarrow x = \frac{1}{2}

Source: Grass-G / M-16 Mathematics Paper 25 Nov First.docx

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