Identify the 16th term of a geometric sequence where a1 = 4 and a8 = -8,748.

a. -172,186,884
b. -57,395,628
c. 57,395,628
d. 172,186,884

Question

Identify the 16th term of a geometric sequence where a1 = 4 and a8 = -8,748.
 
a. -172,186,884	
b. -57,395,628	
c. 57,395,628	
d. 172,186,884

anonymous · Answer

Try computing for it using this formula:
$$a _{n}=a _{1}r ^{n-1}$$

anonymous · Answer

well i need to find r and I cant

anonymous · Answer

@SweetsAndEverything

anonymous · Answer

Let me give you an example. :)
If you will find the element for which the first element is 4 and the common ratio is 2:

$$a _{15}=a _{1}r ^{15-1}$$
$$=4(2)^{14} =2^{2}(2)^{14}$$
=65, 536

Try to follow it from here.

anonymous · Answer

I would be able to follow that if I knew what 'r' equaled... @SweetsAndEverything

anonymous · Answer

I'm not totally sure but I think you need to transpose some of it. I'll try solving it first. :)

anonymous · Answer

okay :)

anonymous · Answer

Can you just give me the answer, I really need to get to bed