medal & fan

Write the explicit formula for the geometric sequence. Then find the fifth term in the sequence.

Question

medal & fan

Write the explicit formula for the geometric sequence. Then find the fifth term in the sequence.

anonymous · Answer

attachment

campbell_st · Answer

can you identify the common ratio in the sequence..?

anonymous · Answer

i don't know how to write the formula

campbell_st · Answer

well the basic formula for a term in a geometric series is 

$$a_{n} = a_{1} \times r^{n - 1}$$

r is the common ratio and n is the number of terms... 

you have 

$$a_{1} = -4$$

so to find the common ration you need to find

$$\frac{a_{2}}{a_{1}}$$

is it the same as 

$$\frac{a_{3}}{a_{2}}$$

so do you have any thoughts on that the common ratio is?