Originally Posted by

**Brazuca** For this problem I already know what the answer is. I just don't know how to get to it. The question is...

Find the second derivative of __Y__ = **x**(Sin**x**)

I know that to get it to __Y'__ I use the product rule which would translate into

[**x**(sin**x**)**'** +**x'**(Sin**x**) which gets me...

__Y'__ = **x**(Cos**x**) + (Sin**x**)

This is the part I am unsure of. What I did after that was

[**x**(Cos**x**)' +**x'**(Cos**x**) + (Sin**x**)**'**] Which gave me...

**x**(-Sin**x**) + (Cos**x**) + (Cos**x**)

My end result was 2(Cos**x**) + **x**(-Sin**x**)

The answer is suppose to be...

Y'' = 2(Cos**x**) - **x**(Sin**x**)

Can anyone tell me what I did wrong, and explain to me how to get the right answer?