y=6t^-3 + 3t^(-6/3) calculate to the y" and y"' I was correct on the second degree derivative, but the third isnt correct and I dont know why.

Question

y=6t^-3 + 3t^(-6/3)   calculate to the y" and y"'  I was correct on the second degree derivative, but the third isnt correct and I dont know why.

anonymous · Answer

bunch of power rules. what did you get from second derivative ?

saifoo.khan · Answer

Last question for today Sat, http://openstudy.com/study#/updates/4f4314ece4b065f388dc8450

laddiusmaximus · Answer

72t^-5 + 18t^-4  i got that one correct

anonymous · Answer

must be reading it wrong, because it looks like you wrote 
$$t^{\frac{-6}{3}}$$ which doesn't make sense

anonymous · Answer

if what you have is right, use the power rule again, get 
$$-320t^{-6}-72t^{-5}$$

laddiusmaximus · Answer

thats what I put. but the program is saying its wrong. hence my confusion

anonymous · Answer

webassign?

laddiusmaximus · Answer

webworks

anonymous · Answer

then ignore it, maybe there is a mistake. seems unlikely you can get the second derivative correct, use nothing but the power rule and get the third derivative incorrect.

laddiusmaximus · Answer

you know? i actually understand the power rule and second and third derivatives pretty well, so I was like what?