Which choice is the explicit formula for the geometric sequence, -0.1, 0.03, -0.009, 0.0027, -0.00081

A.an = -0.1(0.3)n-1
B.an = 0.3(-0.3)n-1
C.an = -0.1(-0.3)n-1
D.an = 0.1(0.3)n
E.an = 0.1(-0.3)n-1


Please explain how you got your answer please Im about to have to take a test on this and I need it explained so I know how to do it on the test,

-0.1, 0.03, -0.009, 0.0027, -0.00081 is actually
-- 0.1, -- 0.1*(--0.3), -- 0.1*(-- 0.3)^2, -- 0.1*(--0.3)^3, -- 0.1*(-- 0.3)^4, .....
so an = -- 0.1*(-- 0.3)^(n -- 1) ANSWER (C)

Michael Howard was the boy (about 19 now) that I use to tutor who surfs competitively internationally

ANSWER.............C

an = -0.1(-0.3)^(n-1)

a1 = -0.1(-0.3)^(1-1) = -0.1(-0.3)^(0) = -0.1(+1) = -0.1

a2 = -0.1(-0.3)^(2-1) = -0.1(-0.3)^(1) = -0.1(-0.3) = 0.03

a3 = -0.1(-0.3)^(3-1) = -0.1(-0.3)^(2) = -0.1(+0.09) = -0.009

and so forth

If you have questions on this or any other math problem feel free
to let me know how to contact you.......Read Below.......

I tutor free online since moving to France from Florida in June 2011.
Hope this is most helpful and you will continue to allow me to tutor you.
If you dont fully understand or have a question PLEASE let me know
how to contact you so you can then contact me directly with any math questions.
If you need me for future tutoring I am not allowed to give out my
info but what you tell me on ***how to contact you*** is up to you
Been a pleasure to serve you Please call again
Robert Jones.............f
"Teacher/Tutor of Fine Students"