Answer:
lower limit is n=1
upper limit is n=18
n=1 to 18∑(7n-4)
Number of beads = 1125
Step-by-step explanation:
Given series is 3+10+17+24.....
we find the formula to find nth term(explicit formula)
first term (a1) = 3
common difference (d)= 7
total of 18 rows
So we find sum for n =1 to 18
lower limit is n=1
upper limit is n=18
n=1 to 18∑(7n-4)
(b) to find total number of beads we apply sum formula
n=18, a=3, d= 7
S= 9(125)=1125
Number of beads = 1125