wow... that makes me feel dumb. Ha ha. Well thank you very much. I guess I've been looking at sequences too long.
I'm having a little trouble understanding this stuff. Sequences in general, really, but I've chosen a geometric one to list here.
It's a rather simple question but I can't seem to find anything that answers it.
Now, I've tried this problem and this is what I did.Determine the number of terms:
4, 12, 36, ... , 972
Tn = ar^n-1
= 972 = 4(3)^n-1
= 243 = 3^n-1. [243 = 3^5]
Therefore 3^n - 1 = 3^5
There are five numbers in the term.
That's what I've done, yet my textbook tells me that the answer is actually six. I have no idea how they got that and I'm beginning to suspect a typo. Any help?
the problem is you should have equated n - 1 = 5 ---> n = 6
as the formula is written here, we start with n = 1, not 0.
for .........here, (n + 1) gives the number of the term
for ................here, n gives the number of the term
you used the last formula, so starting at n = 1 was correct, the problem is you solved the first equation i mentioned incorrectly.