f (t) = 1/7t^6-5t^4+9t

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- Feb 12th 2008, 11:45 AMplstevens2. Differentiate the following function
f (t) = 1/7t^6-5t^4+9t

- Feb 12th 2008, 11:47 AMTrevorP
Do you know the power rule?

$\displaystyle \tfrac{d}{dx} x^n = nx^{n-1}$ - Feb 12th 2008, 12:50 PMplstevens
no, and i have a horrible teacher, can you take me through the steps, please?

- Feb 12th 2008, 12:53 PMPulsar06
Well, there's one rule and one property you have to know here. First is the power rule, as described above. Second is the fact that the derivative of x + y is the (derivative of x) + (derivative of y). In other words, differentiate each term separately, then add up all the derivatives at the end. Does this help?

- Feb 12th 2008, 12:53 PMTrevorP
Basically take whatever number that the variable is raised to. Multiply it by whatever constant was there before and then subtract 1 from the power.

So:

$\displaystyle \tfrac{d}{dx}x^2 = 2x$

$\displaystyle \tfrac{d}{dx}2x = 2$

$\displaystyle \tfrac{d}{dx}3x^{5.9} = 3 \cdot 5.9 x^{4.9}$

It's like that. - Feb 12th 2008, 04:50 PMplstevens
so is that the way you work out the problem that i'm currently doing because i'm still lost and still confused.

- Feb 12th 2008, 05:45 PMPulsar06
- Feb 12th 2008, 06:23 PMplstevens
(6/7)t^5-20t^3+9t^0 is this right, tell me what i'm supposed to do with the 9t^0

- Feb 12th 2008, 07:06 PMtopsquark