Calculating the second derivative.

I have an answer in my solutions manual that I think might be a typo. It is my understanding right now that the second derivative of x is 0. So if that is correct then the second derivative of the equation at the top of my post should then be:

I want to make sure I have not made an error.

My answer:

Thank in advance...

Re: Calculating the second derivative.

Quote:

Originally Posted by

**sepoto**
I have an answer in my solutions manual that I think might be a typo. It is my understanding right now that the second derivative of x is 0. So if that is correct then the second derivative of the equation at the top of my post should then be:

I want to make sure I have not made an error.

My answer:

Thank in advance...

Yes, you made an error. You can apply the quotient rule. You can apply the product rule to . But, you cannot take the derivative of the numerator, then the derivative of the denominator, and assume you are getting a correct derivative.

You can also simplify the expression:

Then, the derivative would be and the second derivative would be .

Re: Calculating the second derivative.

Note that I am assuming you know the chain rule. If you do not know the chain rule, then you cannot take the derivative of . Instead, you would need to use the quotient rule:

Then apply the quotient rule again to find the second derivative.