anonymous one year ago Given an exponential function for compounding interest, A(x) = P(.77)x, what is the rate of change?

1. anonymous

@paki

2. paki

To find rate we subtract the rate in this case is .77 or 77% - 1 or 100% and that would give you the rate in this case its decreasing by an 18%

3. freckles

I thought rate of change was derivative...

4. anonymous

I dont know:(

5. freckles

rate of change is derivative

6. anonymous

What did you get as an answer?

7. freckles

I think he thought you were looking for the interest rate

8. freckles

$A=P(.77)^x \\ \frac{A}{P}=(.77)^x$ P is a constant take ln( ) of both sides

9. freckles

this will allow you to bring down that power of x

10. freckles

and then differentiate both sides

11. anonymous

ok:)

12. anonymous

I got 23% as an answer?!

13. freckles

wait? does that mean you aren't looking for rate of change and you are looking for interest rate?

14. anonymous

no! I think i am looking for rate of change. Why dont we just try out both?

15. anonymous

−0.13% −13% 0.23% −23% these are the answer choics

16. freckles

none of those are the rate of change so you must be looking for interest rate

17. anonymous

yes :)

18. freckles

@paki gave you the way to calculate the interest rate above just do 77%-100%

19. anonymous

-23?

20. anonymous

@paki

21. freckles

yes 77-100 is -23

22. freckles

so 77%-100% is -23%

23. anonymous

Thanks :)