# Finding Values of x

• Dec 5th 2007, 08:42 AM
blurain
Finding Values of x
1)For what values of x is the graph of y=e^-x^2 concave down?

I am not sure how to go about doing this problem, so please, any advice or steps on how to complete the problem will be much appreciated.

-M
• Dec 5th 2007, 08:44 AM
colby2152
Quote:

Originally Posted by blurain
1)For what values of x is the graph of y=e^-x^2 concave down?

I am not sure how to go about doing this problem, so please, any advice or steps on how to complete the problem will be much appreciated.

-M

Find the second derivative and set it equal to zero. Solve for all values of x and test in between those values to see if you get a negative or positive number. Negative results mean it is concave down within that sub-domain.
• Dec 5th 2007, 09:01 AM
blurain
I'm not sure how to find the derivative of y=e^-x^2?
• Dec 5th 2007, 10:50 AM
colby2152
Quote:

Originally Posted by blurain
I'm not sure how to find the derivative of y=e^-x^2?

Chain Rule..
\$\displaystyle f(x)=e^{g(x)}\$
\$\displaystyle f'(x)=g'(x)e^{g(x)}\$