SOLUTION: the sequence of the number x is 17, if the number of the second sequence is 3, what is the number of the first sequence. . . . X is the 17th number of the sequence. 3 is the 3

Algebra ->  Sequences-and-series -> SOLUTION: the sequence of the number x is 17, if the number of the second sequence is 3, what is the number of the first sequence. . . . X is the 17th number of the sequence. 3 is the 3      Log On


   

Question 969239: the sequence of the number x is 17, if the number of the second sequence is 3, what is the number of the first sequence.
.
.
.
X is the 17th number of the sequence.
3 is the 3rd number of the sequence.
Find a%5B1%5D.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
a%5Bn%5D=a%5B1%5D%2B%28n-1%29d
.
.
.
a%5B17%5D=a%5B1%5D%2B%2817-1%29d=X
a%5B1%5D%2B16d=X
.
.
.
a%5B2%5D=a%5B1%5D%2Bd=3
Subtracting this from the first equation,
a%5B1%5D%2B16d-a%5B1%5D-d=X-3
15d=X-3
d=%28X-3%29%2F15
Then,
a%5B1%5D%2B%28X-3%29%2F15=3
a%5B1%5D=3-%28X-3%29%2F15
a%5B1%5D=45%2F15-%28X-3%29%2F15
a%5B1%5D=%2845-X%2B3%29%2F15
highlight%28a%5B1%5D=%2848-X%29%2F15%29