What is the 7th term of the geometric sequence -1, 3, -9, ...?

Question

anonymous · Answer

$$a _{1} = -1 $$
This is the first term of the geometric sequence.

anonymous · Answer

r or the common ratio is 
$$r = 3/-1 = -3 $$
$$r = -9/3 = -3 $$
so $$r = -3 $$

anonymous · Answer

NOW USE THIS FORMULA 
$$a _{n} = a _{1} * r ^{n-1}$$

anonymous · Answer

where $$a _{1} = -1 $$
and $$r = -3 $$
and $$n = 7 $$ since that is the number ur trying to find.

anonymous · Answer

Is it -729

geerky42 · Answer

attachment

anonymous · Answer

HAHAHA
jesus lolol

anonymous · Answer

http://25.media.tumblr.com/5a20340849473ef585e241e274e93d34/tumblr_mjc29wbU0d1r8e5nvo1_400.gif

anonymous · Answer

$$a _{7} = -1 * (-3)^{7-1}$$
$$a _{7} = -1 * (-3)^{6}$$
$$a _{7} = -1 * (729)$$
$$a _{7} = -729$$

anonymous · Answer

I have one more if you wouldnt mind?

geerky42 · Answer

haha

sure

anonymous · Answer

sure :D

anonymous · Answer

CooooooooOOOOOOL k

anonymous · Answer

What is the sum of the geometric sequence 1, -4, 16, ... if there are 7 terms?
 	
	-5,461
	5,461
	-3,277
	3,277

anonymous · Answer

$$a _{1} = 1$$
$$a _{2} = -4$$
$$a _{3} = 16$$
$$r = -4/1 = -4 $$
$$r = 16/-4 = -4 $$
so $$r = -4 $$

anonymous · Answer

This is not the answer its is just the basic things your suppose to know of the geometric sequence to start.

anonymous · Answer

$$a _{1} = 1 * -4 = -4 $$
$$a _{2} = -4 * -4 = 16$$
$$a _{3} = 16 * -4 = -64$$
$$a _{4} = -64 * -4 = 256$$
$$a _{5} = 256 * -4 = -1024$$
$$a _{6} = - 1024 * -4 = 4096$$
$$a _{7} = 4096 * -4 = -16384$$

anonymous · Answer

now add them up.

anonymous · Answer

3,227 :)

anonymous · Answer

Thank you I really appreciate it!

anonymous · Answer

no problem :)