Question

Please hurry, Find the sum of the first 10 terms in the series:

-3, 9, -27, 81...

a.
-14763
c.
44286
b.
4920
d.
59049

Answer 1

`\huge \boxed{\mathrm{\bold{C.} \ 44286}}`

Explanation:

-3, 9, -27, 81...

The common ratio can be found by taking the quotient of a term in the sequence and the previous term.

`\displaystyle (9)/(-3) =-3`

The common ratio is -3.

A term in the sequence multiplies itself by -3 to get the next term.

The nth term for the sequence is :
`a_n=(-3)^n`

The first 10 terms of the sequence are :

-3, 9, -27, 81, -243, 729, -2187, 6561, -19683, 59049

Adding these 10 terms :

-3 + 9 + -27 + 81 + -243 + 729 + -2187 + 6561 + -19683 + 59049

⇒ 44286

Answer 2

44,286

Explanation:

The rule is multiplying by -3.

The sequence goes -3, 9, -27, 81, -243, 729, -2187, 6561, -19683, 59049

Add all of those up and you get 44,286