Differentiation - cant remember

[pat666]

Homework Statement

for the question and attempt see the attachment. I've nearly done this but from my ti-89 I know that i am missing a 2x from the top line and i can't find where its gone. been a while since I've done this and i think that its just a simple mistake... ps it does want the double differential but once i get the first diff right i should be able to finish it off... thanks for any help.

Homework Equations

The Attempt at a Solution

 

[Mark44]

Homework Statement

for the question and attempt see the attachment. I've nearly done this but from my ti-89 I know that i am missing a 2x from the top line and i can't find where its gone. been a while since I've done this and i think that its just a simple mistake... ps it does want the double differential but once i get the first diff right i should be able to finish it off... thanks for any help.

Homework Equations

The Attempt at a Solution

The 2x is missing because you forgot that you need to use the chain rule.

 

[pat666]

so i did- thanks for that.