SOLUTION: Find the next term of the sequence. 1, 8, 27, 64, ... What is the formula for the following arithmetic sequence? -2, 3, 8, 13, ... a.an = -2n + 3

Algebra ->  Sequences-and-series -> SOLUTION: Find the next term of the sequence. 1, 8, 27, 64, ... What is the formula for the following arithmetic sequence? -2, 3, 8, 13, ... a.an = -2n + 3       Log On


   

Question 82554: Find the next term of the sequence.
1, 8, 27, 64, ...


What is the formula for the following arithmetic sequence?
-2, 3, 8, 13, ...
a.an = -2n + 3
b.an = -2n + 7
c.an = 5n + 3
d.an = 5n - 7



What is the common difference of the sequence?
2, -1, -4, -7, ...


Found 2 solutions by 303795, checkley75:
Answer by 303795(602) About Me  (Show Source):
You can put this solution on YOUR website!
The first sequence is cube numbers 1%5E3, 2%5E3, 3%5E3, 4%5E3 so the next number would be 5%5E3=125.
The second problem has a common difference of 5. Testing last two choices which contain 5n shows that the correct answer is 5n-7.
The common difference is -3 as each term is three less than its predecessor.

Answer by checkley75(3666) About Me  (Show Source):
You can put this solution on YOUR website!
1=1*1*1
8=2*2*2
27=3*3*3
64=4*4*4
125=5*5*5
------------------------------
-2,3,8,13,18,23,28,
D) 5n-7 5*2-7=7, 5*3-7=8, 5*4-7=13, 5*5-7=18 (a simplier factor is +5)
-------------------------------
2,-1,-4,-7 (-3) is the common difference.
-------------------------------