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Mathematics 8 Online
OpenStudy (anonymous):

Given an exponential function for compounding interest, A(x) = P(1.04)x, what is the rate of change?

OpenStudy (campbell_st):

find the 1st derivative... thats the rate of change in future value A with respect to time x

OpenStudy (anonymous):

in this equation, is 1.04 what you're using as the slope? @nincompoop

OpenStudy (campbell_st):

now, 1.04 is the base of the exponent

OpenStudy (anonymous):

I still don't understand... im sorry. this chapter confuses me

OpenStudy (campbell_st):

ok... do you know how to differentiate an exponential function...?

OpenStudy (anonymous):

is that where you do the log?

OpenStudy (campbell_st):

if \[y = e^{f(x)}\] then \[y' = f'(x) \times e^{f(x)}\]

OpenStudy (campbell_st):

nope its not logs...

OpenStudy (anonymous):

yeah I don't know any of this...

OpenStudy (campbell_st):

ok.... have you done any calculus...?

OpenStudy (anonymous):

no this is algebra 2

OpenStudy (campbell_st):

ok.... then take makes it hard... have you been given any information such as x = 0 A = $5000, then x = 10 A = 7401... anything like that?

OpenStudy (nincompoop):

the interest rate would be 0.04 or 4%

OpenStudy (nincompoop):

may I, @campbell_st ?

OpenStudy (campbell_st):

ok....lol... I just realised

OpenStudy (nincompoop):

so we first have to know the formula for compounded interest in terms of period. future value = present value * (1+ interest)^(number of period)

OpenStudy (anonymous):

that sounds familiar @nincompoop

OpenStudy (nincompoop):

A(x) = P(1.04)x A(x) will be your future value P is the present value (1.04) is your (1 + interest rate) ^x will be the terms or how many times it will needed to be applied interest rate is your rate of change because it determines how much the amount will be compounded

OpenStudy (nincompoop):

since you were given P(1.04)^x it means that the interest would be 1.04 - 1

OpenStudy (anonymous):

but isn't the rate/compound(n) ? @nincompoop

OpenStudy (campbell_st):

lol... the interest rate is the rate of change... % per annum... or % per year

OpenStudy (anonymous):

ohhh okay! I understand now!

OpenStudy (anonymous):

thank you so much boys :) @campbell_st @nincompoop

OpenStudy (nincompoop):

the exponent x just determines the period. meaning how long will this compounded interest will be applied. 1 year, 2 years 10 years etc.

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