Question

find the 12th term of the geometric sequence 2,-4,8…

Answer 1

Answer:

-4096

Step-by-step explanation:

Formula of geometric sequence is

$a _{1} (r {}^{n - 1} )$

where a1 is the first term of geometric series, R is the common ratio and n is the nth term of the sequence.

the first term is 2 so a1=2

Common ratio is -2

N term is 12

$2( - 2 {}^{12 - 1} ) = 2( - 2 {}^{11} )$

So we get

$- 4096$

Answer 2

Answer:

Step-by-step explanation:

Hi there!

The given geometric sequence is: 2,-4,8.....

Then,

1st term = 3

Common ratio = t2/t1

                         = -4/2

                          = -2

We have,

General term of geometric sequence = a*$r^{n-1}$

Where "n" is no. of terms

an = a*$r^{n-1}$

or, a12 = 2*$-2^{12-1}$

            = 2*-2048

             = -4096

Therefore, the 12th term is -4096.

Hope it helps!