Functions Question 220

Question: $ \underset{n\to \infty }{\mathop{\lim }},{{( \frac{n}{n+y} )}^{n}} $ equals

[AMU 1999]

Options:

A) 0

B) 1

C) 1/v

D) $ {e^{-y}} $

Show Answer

Answer:

Correct Answer: D

Solution:

$ \underset{n\to \infty }{\mathop{\lim }}{{( \frac{n}{n+y} )}^{n}}=\underset{n\to \infty }{\mathop{\lim }}{{( \frac{1}{1+\frac{y}{n}} )}^{n}} $ $ =\underset{n\to \infty }{\mathop{\lim }}{{( 1+\frac{y}{n} )}^{-n}} $ $ =\underset{n\to \infty }{\mathop{\lim }}{{[ {{( 1+\frac{y}{n} )}^{n}} ]}^{-1}}={e^{-y}} $ .