The surface area of an oil spill gets 105% larger every day, represented by the function
s(x) = (1.05)x − 1. On the first day, it covered an area of 31 square meters. Which function would be used to find the area of the oil spill on the 15th day?

s(x) = (1.05)31 − 1

s(x) = (1.05)x − 31

s(x) = 1.05(31)x − 1

s(x) = 31(1.05)x − 1

Question

The surface area of an oil spill gets 105% larger every day, represented by the function 
s(x) = (1.05)x − 1. On the first day, it covered an area of 31 square meters. Which function would be used to find the area of the oil spill on the 15th day?

 s(x) = (1.05)31 − 1

 s(x) = (1.05)x − 31

 s(x) = 1.05(31)x − 1

 s(x) = 31(1.05)x − 1

anonymous · Answer

@dan815

anonymous · Answer

@campbell_st

campbell_st · Answer

can I just check the equation 

is it 

1. $$s(x) = (1.05)^{x - 1}$$

campbell_st · Answer

or 

2. 

$$s(x) = (1.05)\times x - 1$$

anonymous · Answer

x-1 is raised.

campbell_st · Answer

well it looks like exponential growth to me

so 

31 m^2  is the initial area and x is the number of days

so the equation will be 

$$s(x) = 31(.05)^{x - 1}$$

then the to find the area on the 15th day, substitute x = 15 into the equation. 

This is simply the compound interest formula is a slightly different situation...