Derivative of a Vector Function

[p.ella]

Homework Statement

r(t) = ln ti + j, t > 0

find r′ (t) and r″(t)

Homework Equations

none

The Attempt at a Solution

r'(t)= 1/t i

am I on the right track? The answer in the back is r'(t)= 1/t i -1/t^2 j

Please help asap this is quite urgent! Thank you!

 

[Char. Limit]

That doesn't make too much sense if r(t) is supposed to be constant along the j unit vector. My best guess is that it's probably a misprint, and that r(t) is supposed to be r(t)=ln(t) i + 1/t j. That said, if this is for an assignment, proceed with the problem as written, which you're on the right track so far.

 

[p.ella]

That doesn't make too much sense if r(t) is supposed to be constant along the j unit vector. My best guess is that it's probably a misprint, and that r(t) is supposed to be r(t)=ln(t) i + 1/t j. That said, if this is for an assignment, proceed with the problem as written, which you're on the right track so far.

yea that's what I originally thought too, thanks a bunch! (: