Question

Help 10 points for correct answer asap

Answer 1

Final answer is
`S_n=565.5`.

Explanation:

Given that
`a_1=12`,
`a_n=75`, and
`n=13`.

Using those values, we need to find the value of
`S_n`.

Plug these values into sum formula :

`S_n=(n)/(2)\left(a_1+a_n\right)`

`S_n=(13)/(2)\left(12+75\right)`

`S_n=(13)/(2)\left(87\right)`

`S_n=(1)/(2)\left(1131\right)`

`S_n=565.5`

Hence final answer is
`S_n=565.5`.