Question

Find the 10th term of the geometric sequence 10,-20,40,..

Answer 1

`-5120`

Explanation:

From the geometric sequence, we find that the first term is a=10 and the common ratio is r= -2.

So, the 10th term is:

`a_(n)=ar^(n-1)\\a_(10)=10\cdot(-2)^(10-1)\\a_(10)=-5120`