Answer:
Lower limit of the sum: 0
Upper limit of the sum: 17
Explicit formula: ∑(3+7i)
Step-by-step explanation:
Noting that each row has 7 more beads than the previous one and that the series also begins with 3, the formula is:
∑(3+7i)
The lower limit is 0, since 3+ (7 * 0) = 3
When i = 0 you get the value of beads from the first row, when i = 1 you get the value of beads from the second row and so on. Given this, the upper limit is 17.