Question

Consider the following geometric sequence. -5, 10, -20, 40,... If the recursive formula for the sequence above is expressed in the form an=b(cn-1)nwhat is b and c

Answer 1

The formula of the geometric sequence is the following :

`u_n=bc^(n-1)` wherein b is the first term and c is the rate.
From the given data we deduce the parameters:

`c=(10)/(-5)=-2,b=-5`
Therefore:

`u_n=-5(-2)^(n-1)`