ANSWER:
![\begin{gathered} A\left(n\right)=a_(n-1)* 2 \\ A\left(n\right)=0.05\cdot\left(2\right)^(n-1) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/twk1bnwefiydja0x3gyhk9c0en3fu46831.png)
Explanation:
We have that the Arnolds family are going to save a nickel on the first day of the month and then double the amount each day.
One nickel is equal to $0.05, therefore, we can make an recursive formula, it is a geometric sequence where the initial value is 0.05 and the ratio is equal to 2, because it doubles every day, therefore:
![A(n)=0.05\cdot(2)^(n-1)](https://img.qammunity.org/2023/formulas/mathematics/college/eyhv5ylvieydr1bpqtqmbjc47m6wf1qya9.png)
Now, from the above we can deduce the explicit formula, since the next value will be double the previous value, therefore, the explicit formula would be:
![A(n)=a_(n-1)*2](https://img.qammunity.org/2023/formulas/mathematics/college/6x3bf9sgf09slugjya15uu0dhdgyh247b4.png)
Therefore, the correct answers are the 1st and 4th options.