Question

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 + ...

If you were to write this series in summation notation, give

the lower limit of the sum

the upper limit of the sum

the explicit formula of the sum

Answer 1

seventeen

Explanation:

Answer 2

Lower limit of the sum: 0

Upper limit of the sum: 17

Explicit formula: ∑
`_(i=0) ^(17)`(3+7i)

Explanation:

Noting that each row has 7 more beads than the previous one and that the series also begins with 3, the formula is:

∑
`_(i=0) ^(17)`(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.