I can't get the right answer for these two, mainly because they include trigonometry and lns.

http://img530.imageshack.us/img530/9818/1011xt0.png

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- May 27th 2007, 11:52 AMSportfreundeKeaneKentRates-Change with lns and sin/cos
I can't get the right answer for these two, mainly because they include trigonometry and lns.

http://img530.imageshack.us/img530/9818/1011xt0.png - May 27th 2007, 12:12 PMJhevon
For the first:

(a)

we want

(b)

we want

Now

Do you know how to find the derivative of ln ?

(c)

I assume the original score is to be taken when

This means the original score is 72

we want to know when does the average score becomes less than

So we must solve for

we want such that:

- May 27th 2007, 12:25 PMJhevon
The second

The rate of change of voltage is

Now, ........By the Chain rule

we want such that

That is, we want to solve

EDIT 1: added and to the solutions

EDIT 2: Thanks for looking out behemoth100...would you believe that I intentionally left the answer incomplete to see if SportfreundeKeaneKent would catch it? - May 27th 2007, 01:06 PMbehemoth100
Ok well given that its only 7am in the morning this may be a stupid comment but...

Isnt sin(t) = 0 at 0 pi and 2pi? The interval is 0<t<2pi (except they are equal to or less than signs).

So isn't your answer incomplete?

If I have made a mistake on BASIC DIFFERENTIATION AND TRIG THEN I SHOULD BE SHOT!!! I'm scared agaist going up against the almighty Jhevon:eek: - May 27th 2007, 01:08 PMJhevon
- May 27th 2007, 03:48 PMSportfreundeKeaneKent
Nah, I wouldn't have caught that, I'm new to this stuff. Thanks anyways, with the first one.