Answer:
f(x) = 86(1.04)x; grows approximately at a rate of 0.4% daily
Explanation:
The base of the exponential function is 1.29 for 7 days, as in
f(x) = 86*(1.29)^x
The new rate for days can be calculated by dividing x by 7 (where x remains the number of weeks), namely
f(x) = 86*1.29^(x/7)
Using the law of exponents, b^(x/a) = b^(x*(1/a)) = (b^(1/a))^x
we simplify by putting b=1.29, a=7 to get
f(x) = 86*(1.29^(1/7))^x
f(x) = 86*(1.037)^x since 1.29^(1/7) evaluates to 1.037
Rounding 1.037 to 1.04 we get a (VERY) approximate function