If an object is moving along a path that can be described as f(t)=18/(t+2)m between t = 0.5 s
and t = 2 s, where x is in seconds and f(t ) is in meters. What is the object’s instantaneous rate of
change at t = 1.25 s?

Question

If an object is moving along a path that can be described as f(t)=18/(t+2)m between t = 0.5 s
and t = 2 s, where x is in seconds and f(t ) is in meters. What is the object’s instantaneous rate of
change at t = 1.25 s?

retireed · Answer

First you need to take the derivate of ....

    f(t) = 18/(t+2)

canada907cat · Answer

f'(t)=-(18/(x+2)^2)

retireed · Answer

derivative*

canada907cat · Answer

sorry I meant to put t instead of x

retireed · Answer

That looks correct, that was the hard part, now just solve for f'(t) when t is 1.25.

canada907cat · Answer

t=-1.70 m/s ?

retireed · Answer

I need to get my calculator to check it, but it looks to be in the right ballpark.

canada907cat · Answer

Lol okay cool, let me know though just to make sure.

retireed · Answer

That's what I got.... good job!

canada907cat · Answer

Okay great! thank you so much!