by looking at the expression, we can pretty much see who's the common factor and first term.
![\bf \qquad \qquad \textit{sum of a finite geometric sequence} \\\\ S_n=\sum\limits_{i=1}^{n}\ a_1\cdot r^{i-1}\implies S_n=a_1\left( \cfrac{1-r^n}{1-r} \right)\quad \begin{cases} n=n^{th}\ term\\ a_1=\textit{first term's value}\\ r=\textit{common ratio} \end{cases} \\\\[-0.35em] \rule{34em}{0.25pt}](https://tex.z-dn.net/?f=%5Cbf%20%5Cqquad%20%5Cqquad%20%5Ctextit%7Bsum%20of%20a%20finite%20geometric%20sequence%7D%0A%5C%5C%5C%5C%0AS_n%3D%5Csum%5Climits_%7Bi%3D1%7D%5E%7Bn%7D%5C%20a_1%5Ccdot%20r%5E%7Bi-1%7D%5Cimplies%20S_n%3Da_1%5Cleft%28%20%5Ccfrac%7B1-r%5En%7D%7B1-r%7D%20%5Cright%29%5Cquad%0A%5Cbegin%7Bcases%7D%0An%3Dn%5E%7Bth%7D%5C%20term%5C%5C%0Aa_1%3D%5Ctextit%7Bfirst%20term%27s%20value%7D%5C%5C%0Ar%3D%5Ctextit%7Bcommon%20ratio%7D%0A%5Cend%7Bcases%7D%0A%5C%5C%5C%5C%5B-0.35em%5D%0A%5Crule%7B34em%7D%7B0.25pt%7D)
![\bf \sum\limits_{n=1}^{4}~(\stackrel{\stackrel{a_1}{\downarrow }}{-2})(\stackrel{\stackrel{r}{\downarrow }}{-3})^{n-1}\qquad \begin{cases} n=n^{th}\ term\\ a_1=\textit{first term's value}\\ r=\textit{common ratio}\\[-0.5em] \hrulefill\\ a_1=-2\\ r=-3\\ n=4 \end{cases} \\\\\\ S_4=-2\left( \cfrac{1-(-3)^4}{1-(-3)} \right)\implies S_4=-2\left( \cfrac{1-81}{1+3} \right) \\\\\\ S_4=-2\cdot \cfrac{-80}{4}\implies S_4=-\cfrac{-80}{2}\implies S_4=40](https://tex.z-dn.net/?f=%5Cbf%20%5Csum%5Climits_%7Bn%3D1%7D%5E%7B4%7D~%28%5Cstackrel%7B%5Cstackrel%7Ba_1%7D%7B%5Cdownarrow%20%7D%7D%7B-2%7D%29%28%5Cstackrel%7B%5Cstackrel%7Br%7D%7B%5Cdownarrow%20%7D%7D%7B-3%7D%29%5E%7Bn-1%7D%5Cqquad%0A%5Cbegin%7Bcases%7D%0An%3Dn%5E%7Bth%7D%5C%20term%5C%5C%0Aa_1%3D%5Ctextit%7Bfirst%20term%27s%20value%7D%5C%5C%0Ar%3D%5Ctextit%7Bcommon%20ratio%7D%5C%5C%5B-0.5em%5D%0A%5Chrulefill%5C%5C%0Aa_1%3D-2%5C%5C%0Ar%3D-3%5C%5C%0An%3D4%0A%5Cend%7Bcases%7D%0A%5C%5C%5C%5C%5C%5C%0AS_4%3D-2%5Cleft%28%20%5Ccfrac%7B1-%28-3%29%5E4%7D%7B1-%28-3%29%7D%20%5Cright%29%5Cimplies%20S_4%3D-2%5Cleft%28%20%5Ccfrac%7B1-81%7D%7B1%2B3%7D%20%5Cright%29%0A%5C%5C%5C%5C%5C%5C%0AS_4%3D-2%5Ccdot%20%5Ccfrac%7B-80%7D%7B4%7D%5Cimplies%20S_4%3D-%5Ccfrac%7B-80%7D%7B2%7D%5Cimplies%20S_4%3D40)
Answer:
14 months
Step-by-step explanation:
150 - 24 = 126 then divided by 9 which = 14 so it will take 14 months to get 150
Answer:
why would delete my answer
Step-by-step explanation:
Answer is 35/7=5
The width is 5 miles long