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.
The numbers represent an arithmetic progression.
The difference between terms is d=7.
S=a1+a2+...+an, a1=3 and
an=a1+(n-1)×d=3+17×7=122
S=(a1+an)n/2=(3+122)×18/2=125×9=1125
