Gujarati
4-2.Quadratic Equations and Inequations
hard

यदि $x, y$ वास्तविक संख्याएं $(real\,numbers)$ इस प्रकार हैं कि $3^{\frac{x}{y}+1}-3^{\frac{x}{y}-1}=24$ तो $(x+y) /(x-y)$ का मान $(value)$ क्या होंगे ?

A

$0$

B

$1$

C

$2$

D

$3$

(KVPY-2010)

Solution

(d)

We have,

$3^{(x / y)+1}-3^{(x / y)-1}=24$

$\Rightarrow \quad 3 \cdot 3^{x / y}-\frac{3^{x / y}}{3}=24 \Rightarrow \frac{8}{3} \cdot 3^{x / y}=24$

$\Rightarrow \quad 3^{x l y}=9 \Rightarrow 3^{x l y}=3^2$

$\Rightarrow \quad \frac{x}{y}=2$

Using componendo and dividendo, we get

$\frac{x+y}{x-y}=\frac{2+1}{2-1} \Rightarrow \frac{x+y}{x-y}=3$

Standard 11
Mathematics

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