Answer:
an = 1/2 (4)^ (n-1)
a6 = 512
Step-by-step explanation:
The formula for a geometric sequence is
an = a1 (r)^(n-1)
where an is the term of the sequence
a1 is the initial term of the sequence
r is the ratio
and n is the term number
We know a1 = 1/2 and r =4
I will assume that x=6 means we want to know the 6th term
an = 1/2 (4)^ (n-1)
We want to find the 6th term
a6 = 1/2 * 4^(6-1)
a6 = 1/2 * 4^5
a6 = 512
2040 = n/2(20+(n-1)4)
4080 = n(20+4n-4)
4080= 20n +4n^2 -4n
1020 = 4n + n^2
n^2 +4n -1020 =0
use common formula (can't write out so just look at answers. sorry)
which gives answers of n=-34 and n=30. since n can only be positive, n=30 so there are 30 rows. I liked that challenge
Answer:
Since I figure you don't need this answer anymore, I'm just using it for free pts
Step-by-step explanation:
