SOLUTION: Dante is making a necklace with 18 rows of tiny beads in which the number of beads per row is given by the series 3+10+17+24+... a). Use summation notation to write the series.

Algebra ->  Sequences-and-series -> SOLUTION: Dante is making a necklace with 18 rows of tiny beads in which the number of beads per row is given by the series 3+10+17+24+... a). Use summation notation to write the series.       Log On


   

Question 853270: Dante is making a necklace with 18 rows of tiny beads in which the number of beads per row is given by the series 3+10+17+24+...
a). Use summation notation to write the series. Explain what the numbers in the summation notation represent in this situation and how you found the expression used in the summation.
b). Find the total number of beads in the necklace. Explain your method for finding the total number of beads.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Necklace Row I -------- 3
Row II------------------10
Row III-----------------17
common difference between rows is 7. d=7
The first row has 3 so a= 3
Number of rows = 18
It is an Arithmatic Progression
The summation +Sn+=+%28n%2F2%29%28+2a+%2B+%28n-1%29d%29

Sn+=+%2818%2F2%29%282%2A3+%2B+%2818-1%29+%2A+7%29
= 9(6+17*7)
= 9(6+119)
=9*125
= 1125
The total beads = 1125