SOLUTION: In a certain type of sequence, each number (except the first two)is the sum of the two numbers before it. For example, such a sequence might look like this: 1,2,5,7,12,19...wher

Algebra ->  Sequences-and-series -> SOLUTION: In a certain type of sequence, each number (except the first two)is the sum of the two numbers before it. For example, such a sequence might look like this: 1,2,5,7,12,19...wher      Log On


   



Question 254290: In a certain type of sequence, each number (except the first two)is the sum of the two numbers before it. For example, such a sequence might look like this:
1,2,5,7,12,19...where 7 is 2+5, 12 is 5+7, and so on.
If the first number of such a sequence is 1, and the tenth number is 111, what is the second number? You must use algebra and your answer must be exact.
I need the answer for this question by the end of today please. Thank you

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
write out the sequence...

s = second number

1
s
s + 1
2s + 1
3s + 2
5s + 3
8s + 5
13s + 8
21s + 13
34s + 21 = 111 ___ 34s = 90 ___ s = 45/17