Applications Of Derivatives Question 358

Question: The point for the curve $ y=xe^{x} $

[MNR 1990]

Options:

A) $ x=-1 $ is minimum

B) $ x=0 $ is minimum

C) $ x=-1 $ is maximum

D) $ x=0 $ is maximum

Show Answer

Answer:

Correct Answer: A

Solution:

Given equation (curve) $ y=xe^{x} $

$ \therefore \frac{dy}{dx}=xe^{x}+e^{x}=e^{x}(1+x) $ and $ \frac{d^{2}y}{dx^{2}}=(x+2),e^{x} $

For maximum or minimum value of $ f(x) $ ,

therefore $ \frac{dy}{dx}=0\Rightarrow x=-1 $ .
$ \therefore {{{ {f}’’(x) }}_{x=-1}}=+ve $

Hence $ f(x) $ is minimum at $ x=-1 $ .