Question

What is the sum of the arithmetic series 18 sigma t-1 (5t-4)?

Answer 1

Question :

What is the sum of the arithmetic series 18 sigma t-1 (5t-4)?

Answer & Step-by-step explanation:

We have to find the sum of Arithmetic series from t = 1 to t = 18 represented by (5t - 4)

The formula to find the sum of an Arithmetic series when first and the last term is known is:

`S_(n)=(n)/(2)(a_(1)+a_(n))`

n = Total number of terms = 18

`a_(1)` = First Term = 5(1) - 4 = 1

`a_(18)` = 18th Term = 5(18) - 4 = 86

Using the values in the above formula, we get:

`S_(18)=(18)/(2)(1+86)\\S_(18)=9(87)\\ S_(18)=783`

Thus, the sum of 18 terms of the given Arithmetic Series is 783.

Answer 2

783

Explanation:

We have to find the sum of Arithmetic series from t = 1 to t = 18 represented by (5t - 4)

The formula to find the sum of an Arithmetic series when first and the last term is known is:

`S_(n)=(n)/(2)(a_(1)+a_(n))`

Here,

n = Total number of terms = 18

`a_(1)` = First Term = 5(1) - 4 = 1

`a_(18)` = 18th Term = 5(18) - 4 = 86

Using the values in the above formula, we get:

`S_(18)=(18)/(2)(1+86)\\\\ S_(18)=9(87)\\\\ S_(18)=783`

Thus, the sum of 18 terms of the given Arithmetic Series is 783.