Math Is Fun Forum

ninjaman

Member

Registered: 2013-10-15

Posts: 61

second and third order derivatives

hello
I have this question and given my answer for second and third derivatives. not sure if its right though

Bob

Administrator

Registered: 2010-06-20

Posts: 10,629

Re: second and third order derivatives

hi ninjaman

Your image is somewhat squashed up and with no equals.  The dy should be ds.  This is what I think you meant:

This is correct

This first term is correct but the second bit is not.

But this is not right.  The sign is wrong and there shouldn't be a 3 there.

And this has gone completely wrong.  You've lost the 3 from the first term and the error above has made the second term wrong too.

I suggest you have a go at d2s/dt^2 again and I'll check again.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

ninjaman

Member

Registered: 2013-10-15

Posts: 61

Re: second and third order derivatives

d^2s/dt = -3sint - cost

d^3s/dt = -3cost - - sint = -3cost +sint

if this isn't right I don't know what is.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,629

Re: second and third order derivatives

hi ninjaman

That's exactly right.  Well done! 

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob