Is the following the general formula for payment amount , at annual interest rate , with the interest compounded times a year over years, with and ?
. . . . .
If so, are you trying to find in terms of and ?
Ian contributes $2000 a month into an account earning interest at a rate of r/year compounded monthly. At the end of 25 years his account will be worth
Find the differential of S.
I'm having trouble calculating the derivative of this equation because there are so many mixed operations. I know the differential is S^(prime)(r)(dy/dx)x but how can I find the differential if I can't find the derivative?
Yes, that's what I'm trying to do. I need to find out the change in S when r increases from 9% to some another percentage.
The question asks me to find how much more would Ian's account be worth if he earned 9.1% instead of 9%, and so on. I know that I can simply plug in .009 and .0091 into the equation and do S(.009)-S(.0091) but the question is asking me to estimate?