# Formula? Simple just a check of my answer.

1. Feb 28, 2013

### andrewkg

Q.
Consider the exponential function Q=r*s^t. Letting q= ln(Q), show that q is a linear function of t by writing it in the form q=b+mt. State the values of b and m.

Ans.

q=(q0-(ln(r*S^t1)-ln(r*s^t2)*t0))-(ln(r*S^t1)-ln(r*s^t2)T0)*t

Im pretty sure its right my main question is about the subscripts.

2. Feb 28, 2013

### pwsnafu

Wait where did all those subscripts come from. They aren't in the original question.

3. Feb 28, 2013

### andrewkg

Well they aren't used in the original question, but when i looked at the value of m (ln(r*s^t)-ln(r*s^t))/t-t) and that would come up with a 0 in the denominator which is undefined plus the value of m is not 0. So i used the subscripts to show a variation in the value of t so that one could reach an actual value of m. is there another way to do this?

4. Feb 28, 2013

### Mute

Have you tried taking the logarithm of both sides of your original equation, Q = r st? The left hand side is just q = lnQ, but what about the right hand side? (Hint: use the rules of logarithms).

5. Mar 1, 2013

### andrewkg

well the right is just ln(r*s^t). I have that in the formula, but i thought it would be good or necessary to specify the value of q and t. Is using subscripts wrong.

6. Mar 1, 2013

### pwsnafu

The point of the question is whether you understand your log laws.

7. Mar 1, 2013

### andrewkg

well I know the log laws i even reviewed them. but is the answer wrong or ?

8. Mar 1, 2013

### andrewkg

because i tested the formula and it worked soo... Im just a bit confused about what do do from here

9. Mar 1, 2013

### pwsnafu

I said it is to test whether you understand your log laws. You seem to be just going by rote.
On top of that, you don't seem to be understanding what the question is asking.

It's wrong. You are over-complicating the question. Start again and think about what we told you.

Another Hint: This is the source of your problem:

Last edited: Mar 1, 2013
10. Mar 1, 2013

### andrewkg

Oh I see. q=lnr*s^t. so q=t*(lnr*s) so m=ln r*t and b=0. Thanks a ton pwsnafu, i tend to make questions a lot more difficult than need be and it really helps to have someone point it out a few times.

11. Mar 1, 2013

### andrewkg

wait nvm the answer is q= t*ln(s)+ln(r) now its right