Question

Please help!!!!

Find the sum of the series
15
1
(2 1)
n
n

  . Show your work.

Answer 1

255

Explanation:

Answer 2

225

Explanation:

Using the basic components of summation ∑

∑n =
`(1)/(2)` n(n + 1) and ∑1 = n

Thus

∑ (2n - 1) ← for n = 1 to 15

= ∑2n - ∑1

= 2∑n - ∑1

= 2 (
`(1)/(2)` n(n + 1)) - n

= n(n + 1) - n ← Evaluate for n = 15 ( the upper value )

= 15 × 16 - 15

= 240 - 15

= 225