Answer:
12
Step-by-step explanation:
Remark
I can't use a symbol for the currency. I'll just get the answer in numbers. You can add the symbol.
Solution
First day: 50
Second day: - 20
Third day: - 18
50 - 20 - 18 = 12
Dr /dt = 7
A = pi r^2
dA / dr = 2pir
dA/dt = dA/dr * dr/dt = 2pir * 7 = 14pir
when r = 12 rate of change of the area = 14*pi*12 = 168pi
= 527.79 cm^2 / minute to nearest hundredth
<span>∑ from 1 to infinity of n^2* e^(-2n) = (e^2 + e^4)/(e^2 - 1)^3 = 0.23768</span>