ABC26GN2071 · Logarithms

Subject: General Aptitude · Chapter: Logarithms · Exam: · Marks: · Difficulty:

If $\log x+\log y=\log (x+y)$, then

(a)$x=y$

(b)$x y=1$

(c)$y=\frac{x-1}{x}$

(d)$y=\frac{x}{x-1}$

Answer

Answer (as printed): D

Explanation

$\log x+\log y=\log (x+y)$ $$\begin{aligned} & \Rightarrow \log (x+y)=\log (x y) \\ & \Rightarrow x+y=x y \Rightarrow y(x-1)=x \Rightarrow y=\frac{x}{x-1} . \end{aligned}$$

Explanation as extracted from the printed page; notation may be imperfect.

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