# Is this equation right?

$$\underbrace{d}_{dt}$$ ($$\dot{x}$$)$$^{2}$$ = 2$$\ddot{x}$$ ??? or is it just 2$$\dot{x}$$ ?

tiny-tim
Homework Helper
welcome to pf!

hi blueberrypies! welcome to pf!

neither

use the chain rule

nevermind. I'm going to work on this more.

Alright, I still haven't figured this out so if anyone can help point out what I'm missing I would greatly appreciate it.

My book has this

But I don't get this. Shouldn't it be

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tiny-tim
Homework Helper
no, that would be ∂L/∂t

for ∂L/∂θ', remember that θ' is just a symbol, you can replace it by x (or anything), and forget the '

no, that would be ∂L/∂t

for ∂L/∂θ', remember that θ' is just a symbol, you can replace it by x (or anything), and forget the '
Ohhh!

I see what you are saying :) Thanks!