SOLUTION: this problem is out of my algebra book on Geometric sequences. It is asking for the 1st (which i think is given in the formula) 4th and 8th terms. If you only do one, please do the

Question 436653: this problem is out of my algebra book on Geometric sequences. It is asking for the 1st (which i think is given in the formula) 4th and 8th terms. If you only do one, please do the 8th term
A(n)= -1.1x(-4)^n-1 (i am using x to mean multiply)
Isn't the given -1.1 the first term? I see that the ratio (also given) is a -4. This is giving me the most problems. I get the 4th term as 70.4 and the 8th term as 18022.4 BUT that leaves all the terms alternating in a postive, negative fashion. Didnt think you could do that. Help please.
Thank you
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
this problem is out of my algebra book on Geometric sequences. It is asking for the 1st (which i think is given in the formula) 4th and 8th terms. If you only do one, please do the 8th term
A(n)= -1.1x(-4)^n-1 (i am using x to mean multiply)
Isn't the given -1.1 the first term? I see that the ratio (also given) is a -4. This is giving me the most problems. I get the 4th term as 70.4 and the 8th term as 18022.4 BUT that leaves all the terms alternating in a postive, negative fashion. Didnt think you could do that. Help please.
A(n)= -1.1x(-4)^(n-1)
---
A(8) = -1.1*(-4)^(7)
A(8) = -1.1*(-16384)
A(8) = 18022.4
=========================
I get what you got.
Yes, r can be negative.
-------------------------
Cheers,
Stan H.
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