Derivative Problem

Oct 2009
123
1
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.
 

mr fantastic

MHF Hall of Fame
Dec 2007
16,948
6,768
Zeitgeist
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.
 
Oct 2009
123
1
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.
 

mr fantastic

MHF Hall of Fame
Dec 2007
16,948
6,768
Zeitgeist
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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