Question

Find the 9th term of the geometric sequence 6,-24,96... ​

Answer 1

Answer:

A9 = 393216

Step-by-step explanation:

the first thing that will help you solve this question is finding the common ratio between each terms

the first thing that I like to do that usually helps is to take the second term (-24) and divide it by the first term (6) --> this will usually help you spot the common ratio fairly quickly

in your case, the common ratio is -4

- you can also check this by following my note above and then multiplying the second term by the common ratio to see if it matches the third term, which it does!

so now you can go about this two different ways

1. solve directly for the 9th term

2. use the nth term formula for geometric sequences

METHOD 1:

if you continue to multiply by -4 to solve for each term you would end up with:

6, -24, 96, -384, 1536, -6144, 24576, -98304, 393216

and you will recieve 393216 as your answer

METHOD 2:

the nth term formula is An = A1*r^(n-1)

where An = the nth term of the sequence

A1 = first term of the sequence (6)

and r = common ratio

using this formula, you would get:

A9 = 6(-4)^8

A9 = 393216

I hope this helped :)