# Thread: Derivative Problem

1. ## Derivative Problem

Can someone please help me out with this... I know it's an easy problem for most of you but i'm having a lot of difficulty.

I need to get the derivative of s (t) = t^5/2 (7-t), t>= 0

The point i get up to and get stuck at is when trying to do the whole product rule thing. I get up to here and have no idea what to do:

s (t) = 6/2t^(3/2) (t-7) + (t^(5/2)) (1)

I'm not sure what to do after that.

2. Originally Posted by agent2421
Can someone please help me out with this... I know it's an easy problem for most of you but i'm having a lot of difficulty.

I need to get the derivative of s (t) = t^5/2 (7-t), t>= 0

The point i get up to and get stuck at is when trying to do the whole product rule thing. I get up to here and have no idea what to do:

s (t) = 6/2t^(3/2) (t-7) + (t^(5/2)) (1)

I'm not sure what to do after that.
I assume you mean $\displaystyle s = t^{5/2} (7 - t)$.

Expand: $\displaystyle s = 7 t^{5/2} - t^{7/2}$.

Now differentiate term-by-term.

3. Thanks... I understand how you got 7t^5/2 ... but i'm not sure how your getting t^7/2 ... I know I should really know this but i'm pretty weak at math which is why i find calculus so hard... I'm still not that great at the lower levels of math.

4. Originally Posted by agent2421
Thanks... I understand how you got 7t^5/2 ... but i'm not sure how your getting t^7/2 ... I know I should really know this but i'm pretty weak at math which is why i find calculus so hard... I'm still not that great at the lower levels of math.
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