Question

If x, y are real numbers such that
$3^{\frac{x}{y}+1}-3^{\frac{x}{y}-1}=24$, then the value of (x + y) / (x - y) is

• A. 0
• B. 1
• C. 2
• D. 3

Answer 1

Answer: (D)

3

$3^{x/y}=t$

$3t-\frac{t}{3}=24\Rightarrow 8t=3\times 24$
$\Rightarrow t=9$
So, $3^{x/y}=t\Rightarrow 3^{x/y}=9$
$\Rightarrow 3^{x/y}=3^2\Rightarrow x=2y$
$\therefore \frac{x+y}{x-y}=\frac{3y}{y}=3$