Question

What is the value of the 11th term in the following geometric sequence? -5, -10, -20, -40

Answer 1

Answer: - 5120

Step-by-step explanation:

The first thing is to find the common ratio , since it is a geometric sequence.

common ratio ( r ) = second term / first term

r = -10/-5

r = 2

Using the formula for the nth term of a geometric sequence ;

$t_{n}$ = a$r^{n-1}$

The 11th term will thus be:

$t_{11}$ = -5 X $2^{10}$

= -5 x 1024

= -5120