Question

Consider the following geometric sequence -5, 10, -20, 40,..... if the recursive formula for the sequence above expressed in the form a(n)=b*c^n-1, determine the value of b and c.

Answer 1

B is -5 and C is -2. Since -5 is the first number, a(1) is bc^0 and that would make c = 1. B would need to be -5. In the second number, since we know b is -5, c would need to be -2 and anything to the 2-1 is just the same value.