Question

What is the sum of the finite arithmetic series?

(–5) + 0 + 5 + 10 + ... + 65

Answer 1

SO is that the full prob? (-5) + 0 + 5 + 10 + ... + 65?

Answer 2

Yes

Answer 3

@PeterPan

Answer 4

HELP ANYONE ?

Answer 5

@phi Please help me

Answer 6

[n/2(2A1+(n-1)d]

Answer 7

What does that mean ? Does that go to the problem to get my answer ?

Answer 8

first get the common difference of the sequence @Kayy_Drizzyy

Answer 9

yes thats the formula to get the series.

Answer 10

Oh kay. Hold on one second. let me figure it out.

Answer 11

Assuming that -5 is a_0, we can characterize the sequence in the following way:\[a_n = (n-1) \cdot 5\] Hence, to find out the index of the last term in the sum, we solve the following equation:\[65 = (i - 1) \cdot 5\]\[\frac{65}{5} = i - 1\]\[i = \frac{65}{5} + 1 = 14\]
So the sum above equals \[\sum_{n=0}^{14}a_n = \sum_{n=0}^{14}(n-1)\cdot 5 = 5\cdot \sum_{n=0}^{14}(n-1) = 5\cdot (\sum_{n=0}^{14}n - \sum_{n=0}^{14}1)\]\[= 5\cdot \sum_{n=0}^{14}n - 5\cdot 14 = 5\cdot \frac{14\cdot 15}{2} - 5 \cdot 14 = 455\]

Answer 12

Thank you @Stiwan that really helps a lot.

Answer 13

\[18Sigmat=1\]

Answer 14

\[\sum_{t=1}^{18}\]

Answer 15

I'm sorry, I really don't get what that's supposed to mean

Answer 16

i was testing something out sorry

Answer 17

is this problem is done?

Answer 18

yes