Question

My answer is C

What is the sum of a 30-term arithmetic sequence where the first term is 74 and the last term is -100? (3 points)
Answer

-468

-442

-416

-390

Answer 1

no, its not C, which formula did you use ?

Answer 2

you should have used,
\(\huge S_n = (n/2)(a_1+a_n)\)

Answer 3

arithmetic series formula: S(n) = n[a(1) + a(n)]/2

Answer 4

correct, so n= 30, a1 = 74, an=-100
what you get as Sn ?

Answer 5

30

Answer 6

:O

Answer 7

which calculator are you using ?
make sure you are calculating (30/2)(74-100)=...?

Answer 8

30 (74 - 100)/2

Answer 9

which equals ?

Answer 10

wait why does ours look different?

Answer 11

1st term minus last term i thought

Answer 12

its same, it just 'looks' different,30 (74 - 100)/2 = (30/2)(74-100)

Answer 13

thank god

Answer 14

its 1st term + last term.
a1+an

Answer 15

-390

Answer 16

you are \(\huge \color{red}{\checkmark}\)

Answer 17

wow thank you:)

Answer 18

\[ \begin{array}l\color{red}{\text{w}}\color{orange}{\text{e}}\color{#e6e600}{\text{l}}\color{green}{\text{c}}\color{blue}{\text{o}}\color{purple}{\text{m}}\color{purple}{\text{e}}\color{red}{\text{ }}\color{orange}{\text{^}}\color{#e6e600}{\text{_}}\color{green}{\text{^}}\color{blue}{\text{}}\end{array} \]