Question

PLEASE HELP What is the rule for the sequence with the first four terms below?

-8, 32/5, -128/25, 512/125

A.) f(x)=10(-4/5)^x

B.) f(x)=-8(4/5)^x

C.) f(x)=40(-1/5)^x

D.) f(x)=-8(1/5)^x

Answer 1

A) [First try is correct for all U1 to U4]

Explanation:

1. Trying each option

(let x = 1,2,3,4) since it goes from U1 to U4 (Geometric sequence)

A.) 10(-4/5)^x

10(-4/5)^1 = -8

10(-4/5)^2 = 6.4

10(-4/5)^3 = -5.12

10(-4/5)^4 = 4.096