Question

Find the 14th term of geometric sequence 5,-10,20,...

Answer 1

What he said should be correct.

Answer 2

Explanation:

The formula for a geometric sequence is

`a_n=a_1*r^(n-1)` where n is the position number in the sequence, a1 is the first number in the sequence, and r is the common ratio. For us,

n is 14, a1 is 5, and the common ratio (the number we multiply by each number to get to the next one in line) is -2.

`a__(14)=5*(-2)^(14-1)` and

`a_(14)=5*(-2)^(13)` and

`a_(14)=5(-8192)` so

`a_(14)=-40960`